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first import of structure, PYTHIA8 and DELPHES
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1	<html>
2	<head>
3	<title>Update History</title>
4	<link rel="stylesheet" type="text/css" href="pythia.css"/>
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29
30	<h2>Update History</h2>
31
32	These update notes describe major updates relative to the baseline
33	PYTHIA 8.100 version. However, they are less extensive than the
34	corresponding update notes for PYTHIA 6. On the other hand,
35	whereas the PYTHIA 6 manual is a static document, the PYTHIA 8
36	html/php pages are kept up to date for each subversion.
37
38	<br/><br/>
39	<b>Important note:</b>version 8.160 does introduce some elements of
40	backwards incompatibility. Specifically, "multiple interactions",
41	abbreviated MI, haa been renamed "multiparton interactions", MPI.
42	This affects many parts of the code and documentation. Also some
43	features are deprecated, although remaining until the end of the
44	8.1xx version series.
45
46
47	<h3>Main news by version</h3>
48
49	<ul>
50
51	<li>8.105: 24 February 2008
52	<ul>
53
54	<li>New option to initialize with arbitrary beam directions<br/>
55	<code>pythia.init( idA, idB, pxA, pyA, pzA, pxB, pyB, pzB)</code></li>
56
57	<li>Added capability to set <?php $filepath = $_GET["filepath"];
58	echo "<a href='BeamParameters.php?filepath=".$filepath."' target='page'>";?>beam energy spread
59	and beam vertex</a>.
60	<br/>
61	<b>Warning:</b> as a consequence, the old <code>Beams</code> group of
62	settings has been moved to <code>BeamRemnants</code>, and
63	<code>Beams</code> is now instead used for machine beam parameters.
64	Therefore also some <code>Main</code> settings of this character have been
65	regrouped, as follows:
66	<table cellspacing="5">
67	<tr> <td>8.100 setting </td> <td>has been moved to </td> </tr>
68	<tr> <td><code>Main:idA </code></td>
69	<td><code>Beams:idA </code></td> </tr>
70	<tr> <td><code>Main:idB </code></td>
71	<td><code>Beams:idB </code></td> </tr>
72	<tr> <td><code>Main:inCMframe </code></td>
73	<td>(<code>Beams:frameType</code>) </td> </tr>
74	<tr> <td><code>Main:eCM </code></td>
75	<td><code>Beams:eCM </code></td> </tr>
76	<tr> <td><code>Main:eA </code></td>
77	<td><code>Beams:eA </code></td> </tr>
78	<tr> <td><code>Main:eB </code></td>
79	<td><code>Beams:eB </code></td> </tr>
80	<tr> <td><code>Main:LHEF </code></td>
81	<td><code>Beams:LHEF </code></td> </tr>
82	</table></li>
83
84	<li>The <code>forceHadronLevel()</code> method introduced for standalone
85	hadronization.</li>
86
87	<li><code>main15.cc</code> illustrated how either full hadronization or
88	only decays of some particles can be looped over for the rest of the
89	event retained.</li>
90
91	<li>The <code>LHAevnt</code> and <code>LHAinit</code> classes have been
92	joined into a new <code>LHAup</code> one, with new options that allow
93	the writing of a Les Houches Event File.</li>
94
95	<li>The <code>SusyLesHouches</code> class updated to handle
96	SLHA version 2.</li>
97
98	<li>Updated HepMC conversion routine.</li>
99
100	<li>The static <code>ErrorMsg</code> class has been removed and
101	its functionality moved into the non-static <code>Info</code> class,
102	in the renamed Info file.</li>
103
104	<li>Further reduction of the use of static, with related code changes.
105	This should allow to have several almost independent <code>Pythia</code>
106	instances. Some static classes still remain, however, notably for
107	random number generation and particle properties.</li>
108
109	<li>Limited capability to use two different <code>Pythia</code> instances
110	for signal + pileup event generation, see <code>main19.cc</code> for an
111	example.</li>
112
113	<li>In the <code>Event</code> class the <code>=</code> and
114	<code>=+</code> methods have been overloaded to allow the copying
115	or appending of event records. Illustrated in <code>main19.cc</code>.</li>
116
117	<li>The html and php page formatting improved with
118	cascading style sheets.</li>
119
120	<li>Several minor improvements and new options, including updated configure
121	scripts.</li>
122
123	</ul>
124	</li>
125
126	<li>8.108: 1 May 2008
127	<ul>
128
129	<li>Correction in the event record, so that the beam particles in line
130	1 and 2 do not have any mother according to the <code>motherList</code>
131	method. Previously the "system" entry in line 0 was counted as their
132	mother, which gave rise to an unexpected extra vertex in the conversion
133	to the HepMC format.</li>
134
135	<li>Support for HepMC version 1 is removed, to simplify the code and
136	reflect the evolution of the field.</li>
137
138	<li>Status codes are stored in HepMC only as 1 for existing and 2 for
139	decayed or fragmented particles (whereas previously the original PYTHIA
140	codes were used for the latter).</li>
141
142	<li>Parton densities are stored in HepMC as <i>xf(x,Q^2)</i>
143	rather than the <i>f(x,Q^2)</i> used in (some) previous versions.</li>
144
145	<li>The SusyLesHouches class has ben updated so that reading is fully
146	compatible with the SLHA2 standard. </li>
147
148	<li>Improved handling of the Higgs width, relevant for massive and thereby
149	broad resonance shapes.</li>
150
151	<li>The matrix elements for neutralino pair production have now been
152	completed and checked.</li>
153
154	<li>Ensure that <i>alpha_strong</i> does not blow up, by introducing
155	a minimal scale somewhat above <i>Lambda_3</i> (roughly where
156	<i>alpha_strong = 10</i>).</li>
157
158	<li>New methods <code>isValence1()</code> and <code>isValence2()</code>
159	in the <code>Info</code> class.</li>
160
161	<li>Protection against division by zero in calculation of decay vertex
162	(for zero-mass gluons with zero lifetime, where there should be no
163	displacement).</li>
164
165	<li>A new compilation option <code>-Wshadow</code> is introduced and
166	code is rewritten at all places where this option gave warnings.</li>
167
168	<li>Minor library correction to allow compilation with gcc 4.3.0.</li>
169
170	</ul>
171	</li>
172
173	<li>8.114: 22 October 2008
174	<ul>
175
176	<li>New rescattering description operational (but still experimental)
177	for the case that FSR is not interleaved, but saved until after MPI,
178	ISR and beam remnants have been handled. This involves much new code
179	in several classes.</li>
180
181	<li>A new class <code>PartonSystems</code> is introduced to
182	keep track of which partons in the event record belong to which
183	subcollision system, plus some further information on each subsystem.
184	It takes over functionality previously found as part of the
185	<code>Event</code> class, but leaves room for future growth.</li>
186
187	<li>Add optional model, wherein an increased <i>pT0</i> turnoff scale
188	for MPI and ISR is used for above-average active events, i.e. events that
189	already have several MPI's or ISR emissions.</li>
190
191	<li>Freeze GRV 94L distribution at small <i>Q^2</i> to avoid blowup.</li>
192
193	<li>The <code>pythia.readFile(...)</code> method can now alternatively take
194	an <code>istream</code> as argument instead of a <code>filename</code>.</li>
195
196	<li>Minor bug correction in <code>PartonLevel.cc</code>; the bug could
197	(rarely) give a segmentation fault.</li>
198
199	</ul>
200	</li>
201
202	<li>8.120: 10 March 2009
203	<ul>
204
205	<li>New rescattering description further developed, but not yet
206	recommended for normal usage.</li>
207
208	<li>Include new processes for Large Extra Dimensions and Unparticles,
209	contributed by Stefan Ask. New test program <code>main28.cc</code>
210	illustrates.</li>
211
212	<li>Include further SUSY processes: neutralino-chargino and
213	chargino-chargino pairs. The processes should be valid also
214	in the case of non-minimal flavour violation and/or CP violation.
215	Expanded machinery to keep track of SUSY parameters.</li>
216
217	<li>Include backwards evolution of incoming photon as part of the
218	<code>SpaceShower</code> initial-state radiation description. This
219	allows you to simulate hard collisions where one of the incoming
220	partons is a photon. New test program <code>main43.cc</code>
221	illustrates.</li>
222
223	<li>Allow separate mass and transverse momentum cuts when two hard
224	subprocesses are generated in the same event.</li>
225
226	<li>The default value for the border between short- and long-lived
227	paticles has been changed from 1 mm to 10 mm, to better conform with
228	LHC standards, see <?php $filepath = $_GET["filepath"];
229	echo "<a href='ParticleDecays.php?filepath=".$filepath."' target='page'>";?>here</a>.
230	The default is still to let all unstable particles decay.</li>
231
232	<li>New ISR matrix-element correction to <i>f -> f gamma</i>
233	in single <i>W</i> production.</li>
234
235	<li>New method <code>Event::statusHepMC</code> returns the status
236	code according to the HepMC conventions agreed in February 2009.
237	The interface to HepMC now writes out status according to this
238	convention.</li>
239
240	<li>Add capability to link to FastJet, with expanded configure script
241	and Makefile, and with <code>main61.cc</code> as new example.</li>
242
243	<li>Update of <code>Makefile.msc</code>, with added support for latest
244	Visual C++ Express edition and use of regexp to check nmake version.</li>
245
246	<li>Update of <code>LHAFortran.h</code> and
247	<code>Pythia6Interface.h</code>, to make the interface to Fortran
248	routines work also under Windows. (Thanks to Anton Karneyeu.)
249
250	<li>Updated and expanded worksheet.</li>
251
252	<li>The manual pages in the <code>xmldoc</code> directory, and thereby
253	also those of the <code>htmldoc</code> and <code>phpdoc</code>
254	directories, have been significantly updated and expanded. In particular,
255	in many places the class of each method is explicitly shown, as well as
256	the type of the return value and of the arguments. This upgrade is not
257	yet completed, but already covers the more relevant sections. </li>
258
259	<li>The unary minus operator in the <code>Vec4()</code> returns a
260	reference to a four-vector with all components negated, but leaves
261	the original four-vector unchanged. Previously the four-vector itself
262	was flipped.</li>
263
264	<li>The <code>pPlus()</code> and <code>pMinus()</code> methods of a
265	four-vector and an event-record particle are renamed <code>pPos()</code>
266	and <code>pNeg()</code>, respectively.</li>
267
268	<li>Include a further loop in <code>ProcessLevel</code>, so that a new
269	process is generated in case of failures of a less severe nature.</li>
270
271	<li>Introduce warning message for unexpected <code>meMode</code> in
272	<code>ResonanceWidths</code>.</li>
273
274	<li>Les Houches event reading framework has been rearranged for
275	more flexibility. Some bugs corrected. Specifically, when scale
276	is not set (<code>scale = -1.</code> in the Les Houches standard),
277	PYTHIA did not attempt to set this scale itself, which typically
278	lead to there not being any ISR or FSR. Now the
279	<?php $filepath = $_GET["filepath"];
280	echo "<a href='CouplingsAndScales.php?filepath=".$filepath."' target='page'>";?>rules for normal
281	1-, 2- and 3-body final states</a> are applied, with a trivial
282	extension of the 3-body rules for higher multiplicities.</li>
283
284	<li>Correct bug in the handling of parton densities, whereby it was
285	not possible to switch to a new set, once a first initialization
286	had been done.</li>
287
288	<li>Correct bugs when several <code>Pythia::init</code> initialization
289	calls are made in the same run, specifically in the case that pointers
290	to external processes have been handed in.
291
292	<li>Changes in <code>main03.cmnd</code> and <code>main04.cmnd</code>
293	so that some nonstandard options are commented ou rather than active.
294	Related comments inserted also in some other <code>.cmnd</code> files,
295	but there without any change in program execution.</li>
296
297	<li>A few further minor bug fixes.</li>
298
299	<li>Update year to 2009.</li>
300
301	</ul>
302	</li>
303
304	<li>8.125: 16 June 2009
305	<ul>
306
307	<li>Hadronization and timlike-shower parameter default values updated
308	according to a tune to LEP1 data by Hendrik Hoeth, using the
309	Rivet + Professor framework.</li>
310
311	<li>Many further SUSY production processes. SLHA readin expanded to cover
312	also masses and decay modes. Example <code>main22.cc</code> updated, while
313	<code>main33.cc</code> now superfluous and removed. </li>
314
315	<li>Also further processes for extra dimensions.</li>
316
317	<li>Stefan Ask joins as coauthor.</li>
318
319	<li>The <code>TimeShower::shower(...)</code> method has gained
320	a new argument, that forces the shower evolution to stop after
321	a given number of branchings. A new method
322	<code>TimeShower::pTLastInShower()</code> permits the last evolution
323	<i>pT</i> to be read out. These extensions can be useful
324	for matching studies.
325	</li>
326
327	<li>New optional argument <code>isInterleaved</code> added to
328	<code>TimeShower::branch(...)</code>. Is false by default, but
329	true when called from the parton level for interleaved evolution
330	of several parton systems, optionally also with ISR and MPI.</li>
331
332	<li>New methods <code>UserHooks::canSetResonanceScale()</code>
333	and <code>UserHooks:scaleResonance(...)</code> allows an optional
334	user choice of the maximum shower scale in resonance decays.</li>
335
336	<li>A new method <code>SpaceShower::doRestart()</code> has been
337	added, to help distinguish cases when a
338	<code>SpaceShower::branch(...)</code> failure forces a complete
339	restart of the evolution from ones where only the intended
340	current branching has been vetoed.
341
342	<li>When multiparton interactions are initialized, it is now
343	possible to reduce both <i>pT0</i> and <i>pTmin</i>
344	if necessary to find a valid solution where
345	<i>sigma_jet > sigma_nondiffractive</i>. Previously
346	only the former would be reduced, which could lead to
347	infinite loops if too large a <i>pTmin</i> was used.
348	Thanks to Sami Kama for pointing out the problem.
349	</li>
350
351	<li>The rescattering machinery is now essentially completed, and can
352	be used also by others than the authors. For now, however, it can only
353	be recommended for dedicated studies, not e.g. for generic tunes.
354	</li>
355
356	<li>Timelike and spacelike showers, and beam remnant handling,
357	are modified to handle rescattering partons. Specifically, a new machinery
358	is introduced to trace the recoils from the combination of rescattering
359	with showers and primordial <i>kT</i>. Can assign space- or timelike
360	virtualities to intermediate particles to have energy and momentum
361	conserved locally. This affects the <code>PartonLevel</code>,
362	<code>MultipartonInteractions</code>, <code>TimeShower</code>,
363	<code>SpaceShowe</code>r and <code>BeamRemnants</code> classes.
364	Further details to appear in the upcoming article on rescattering.
365	(Another change is a reversal to pre-8.114 order for non-interleaved FSR,
366	wherein also FSR is treated before beam remnants are attached.)
367	</li>
368
369	<li>Four new status codes introduced, as part of the rescattering
370	description:
371	<br/>45 : incoming rescattered parton, with changed kinematics owing
372	to ISR in the mother system (cf. status 34);
373	<br/>46 : incoming copy of recoiler when this is a rescattered parton
374	(cf. status 42);
375	<br/>54 : copy of a recoiler, when in the initial state of a different
376	system from the radiator;
377	<br/>55 : copy of a recoiler, when in the final state of a different
378	system from the radiator.
379	</li>
380
381	<li>New method <code>Info::tooLowPTmin()</code> can tell whether the
382	<i>pTmin</i> scales for showers or multiparton interactions are too low.
383	</li>
384
385	<li>Pion beams allowed, both <i>pi^+</i>, <i>pi^-</i> and
386	<i>pi^0</i>. New machinery for the latter, where the valence
387	flavour content is chosen to be either <i>d dbar</i> or
388	<i>u ubar</i> for each new event. One internal pion PDF
389	implemented, with others from LHAPDF.</li>
390
391	<li>Treatment of Pomeron-proton collisions begun.</li>
392
393	<li>Phase-space handling of hard processes and multiparton interactions
394	slightly expanded to better allow for harder PDF's than proton ones,
395	e.g. for Pomerons.</li>
396
397	<li>The program documentation has been expanded with an
398	alphabetical index of all methods that are described on the
399	webpages, see the <?php $filepath = $_GET["filepath"];
400	echo "<a href='ProgramMethods.php?filepath=".$filepath."' target='page'>";?>Program Methods</a>
401	page. Also other sections of the documentation have been
402	updated and expanded, including the worksheet.</li>
403
404	<li>Several <code>list</code> methods have been made
405	<code>const</code>. For the listing of events two new methods
406	have been added, <code>Event::list()</code> and
407	<code>Event::list(bool showScaleAndVertex,
408	bool showMothersAndDaughters = false)</code>,
409	that correspond to special cases of the general method.</li>
410
411	<li>A new method <code>Pythia::LHAeventSkip(int nSkip)</code>
412	permits a skip-ahead of the reading of external Les Houches
413	Events, without the necessity to generate the intervening
414	<code>nSkip</code> events in full. Makes use of the new
415	<code>LHAup::skipEvent(int nSkip)</code> method to perform
416	the operations. Mainly intended for debug purposes.
417
418	<li>The <code>ClusterJet</code> jet finder now saves the last
419	five clustering scales. Also a minor bug fix. Thanks to Nils
420	Lavesson for this contribution.</li>
421
422	<li>The <code>Particle::m2()</code> method now returns a negative
423	number when the stored mass <i>m</i> is negative, as used to
424	indicate spacelike virtualities. Also the
425	<code>Particle::eCalc()</code>, <code>Particle::mT()</code> and
426	<code>Particle::mT2()</code> methods have been modified.
427	</li>
428
429	<li>The <code><<</code> method to print our a four-vector has
430	been expanded with a fifth number, the invariant length, with a minus
431	sign for spacelike vectors, and provided within brackets to allow
432	a simple visual distinction.</li>
433
434	<li>New methods <code>Rndm::dumpState(string fileName)</code> and
435	<code>Rndm::readState(string fileName)</code> allows to write or
436	read the state of the random number generator to or from a binary file.
437	</li>
438
439	<li>New method <code>double GammaReal(double x)</code> returns the
440	value of the <i>Gamma</i> function for arbitrary real argument.
441	Some cross sections for extra-dimensional processes rewritten to
442	make use of it.
443	</li>
444
445	<li>New example program <code>main29.cc</code> shows how
446	to set up a fictitious process of a heavy system decaying
447	to two particles or partons, with decays traced to stable
448	particles, as relevant for astroparticle applications.</li>
449
450	<li>Main programs that illustrate the HepMC interface have
451	been updated to use version 2.04, including units and excluding
452	deprecated output formats.</li>
453
454	<li>The <code>main32.cc</code> example extended also to handle
455	Les Houches Event Files.</li>
456
457	<li>The Makefile has been modified so that "make clean" only
458	removes the current compilation and library fles, while
459	"make distclean" gives a more extensive reset and cleanup.
460	Thanks to Nils Lavesson for this contribution. Some other
461	minor Makefile corrections.</li>
462
463	<li>Several main programs that use the
464	<code>Main:timesToShow</code> mode have been corrected so as
465	not to crash if this is set to zero. Also some other cosmetics
466	changes in main programs that do not affect the running.</li>
467
468	<li>Bug correction, in that previously a veto with user hooks
469	was not propagated from parton showers inside resonance decays.
470	</li>
471
472	<li>Minor bug fix in <code>TimeShower</code> for kinematics with
473	unequal beam-particle masses.</li>
474
475	<li>Bug fix so that <code>PartonLevel:MPI = off</code> also works for
476	minimum-bias events.</li>
477
478	<li>Minor bug fix in the impact-parameter selection of multiparton
479	interactions. Thanks to Sami Kama for pointing it out.</li>
480
481	<li>String fragmentation for junction topology protected against
482	numerical instability in boost.</li>
483
484	<li>Bug correction in the handling of particle decays to partons,
485	where the scale of the partons was set before the partons had been
486	added to some arrays, leading to indexation out of bounds.
487	Thanks to Vladislav Burylov for discovering this bug.
488	</li>
489
490	<li>Bug correction in the handling of particles with inhibited decay,
491	where the decay vertex would be too far displaced, which could lead to
492	infinite loop. Thanks to Sami Kama for debugging this. </li>
493
494	<li>Check to avoid infinite loop in matrix-element handling of
495	two-body decays.</li>
496
497	<li>Bug correction to avoid infinite loops in Dalitz decay treatment.
498	Some changes in the decay handling logic to allow a new try when the
499	decay of a particle fails.</li>
500
501	<li>Minor correction, so the pointer to the <code>Info</code> class
502	is set also for user-written classes derived from <code>LHAup</code>.
503	</li>
504
505	<li>Correction for typo in the matrix element of the
506	<code>Sigma3ff2HchgchgfftWW</code> class, for doubly charged Higgs
507	production. Thanks to Merlin Kole for spotting it.</li>
508
509	<li>Updated colour bookkeeping in junction-antijunction annihilation
510	avoids later problems in <code>Pythia::check()</code>. </li>
511
512	<li>Minor updates of the <code>Makefile.msc</code> file to work with
513	Visual Studio 2008. Thanks to David Bailey for these modifications.</li>
514
515	<li>Ensure that <code>nInit</code> in the <code>BeamParticle</code>
516	class is set also for unresolved lepton beams.</li>
517
518	<li>The <code>VetoEvolution</code> class, derived from
519	<code>UserHooks</code>, is obsolete and has been removed.</li>
520
521	</ul>
522	</li>
523
524	<li>8.130: 15 September 2009
525	<ul>
526
527	<li>New machinery that allows multiparton interactions inside diffractive
528	systems. Also new optional Pomeron flux factors and Pomeron PDFs.
529	New page on <?php $filepath = $_GET["filepath"];
530	echo "<a href='Diffraction.php?filepath=".$filepath."' target='page'>";?>diffraction</a> added, where
531	further details are collected. Still not tuned, so to be used with
532	caution.</li>
533
534	<li>Make Peter Skands' "Tune 1" parameters for ISR and MPI default.
535	The older simpler tune is still available as an option, see
536	<code><?php $filepath = $_GET["filepath"];
537	echo "<a href='Tunes.php?filepath=".$filepath."' target='page'>";?>Tune:pp</a></code>.
538	</li>
539
540	<li>New possible choices for a second hard process: charmonium,
541	bottomonium, top pair and single top.</li>
542
543	<li>New code for pair production of generic colour-triplet scalar,
544	fermion or vector. Largely written by Johan Bijnens, partly recycling
545	existing code.</li>
546
547	<li>Add user hooks possibility to veto event after a given number
548	of multiparton interactions.</li>
549
550	<li>Add instructions how PYTHIA 8 can be used from inside ROOT.
551	Thanks to Andreas Morsch for providing the text and Rene Brun
552	for a simple example.</li>
553
554	<li>The <code>main21.cc</code> example extended with an option
555	for a single-particle gun.</li>
556
557	<li>Improvements and bug fixes in rescattering framework.</li>
558
559	<li>New method <code>Hist::table(string fileName)</code> provides a
560	more direct way to print a two-column table of histogram contents
561	into a file than the current <code>Hist::table(ostream& os = cout)</code>.
562	</li>
563
564	<li>Modify reading of external files so that a line only consisting of
565	control characters counts as empty, the same way as a line only consisting
566	of blanks already did. This includes carriage return, tabs and a few more,
567	the ones represented by <code>\n \t \v \b \r \f \a</code>. Applies to
568	Les Houches Event files, settings files and particle data files. </li>
569
570	<li>Fix it so that the read-in of a Les Houches Event File for the
571	hardest process can be combined with the faciliy to select a specified
572	second hard process.</li>
573
574	<li>New empty base class method <code>LHAup::fileFound()</code>
575	allows the derived class <code>LHAupLHEF</code> to signal more
576	clearly that a failed initialization is caused by a failure to open
577	the desired file. </li>
578
579	<li>Check that a pointer to an <code>LHAup</code> object has been set
580	in <code>Pythia::LHAeventList()</code> and
581	<code>Pythia::LHAeventSkip(...)</code> calls.</li>
582
583	<li>Updated configure and Makefile, e.g. to build shared libraries
584	on Mac OS X.</li>
585
586	<li>The options with a direct link to hard-process generation
587	in PYTHIA 6 has been removed. It is hardly ever used but
588	complicates the build structure. (Owing to its usefulness for some
589	debug work, it was reinstated in a limited form in version 8.135.
590	Thus <code>main51.cc</code> now contains the complete interface,
591	previously in separate files, and commented-out lines in
592	<code>examples/Makefile</code> suggest how PYTHIA 6 could be linked.)
593	</li>
594
595	<li>New argument to <code>Info::errorMsg(...)</code> allows to
596	show all error messages of a specific kind rather than only the
597	first one, e.g. for initialization.</li>
598
599	<li>Correction in decay table of righthanded Majorana neutrinos.
600	Thanks to Arnaud Ferrari and Vladimir Savinov.</li>
601
602	<li>Correction in expressions in the manual for <i>H^+-</i> couplings
603	to an <i>h^0</i>, <i>H^0</i> or <i>A^0</i> and a <i>W^+-</i>.
604	Thanks to Rikard Enberg.</li>
605
606	<li>Fix for accessing uninitialized memory, caused by accessing the
607	daughters of the incoming beams before these daughters actually existed.
608	Thanks to David Bailey and Sami Kama.
609	</li>
610
611	<li>Uninitialized photon PDF inside the proton could give crazy results
612	for processes with incoming photons. Thanks to Adam Davison.</li>
613
614	<li>Bug fix such that finite lifetimes can be set also for particles
615	produced in the hard process. To exemplify, the bug affected
616	<i>tau</i> leptons produced in <i>Z^0</i> and <i>W^+-</i>
617	decays. Thanks to Troels Petersen.</li>
618
619	<li>Bug fix in <code>TimeShower</code>, that <code>beamOffset</code>
620	could remain uninitialized. Thanks to Sami Kama.</li>
621
622	<li>Minor correction to resonance decays: fail if the allowed mass
623	range of a Breit-Wigner resonance is a small fraction of the total
624	area under the resonance curve.</li>
625
626	<li>Correction when all three valence quarks were kicked out from a
627	proton and could give false messages that beam momentum had been
628	used up.</li>
629
630	<li>Clarify status codes needed for hadron-level standalone runs in
631	order to avoid error messages, and modify the <code>main21.cc</code>
632	example accordingly. </li>
633
634	<li>Minor corrections in the processes for extra dimensions.</li>
635
636	<li>Some other minor additions to existing facilities
637	and minor bug fixes.</li>
638
639	</ul>
640	</li>
641
642	<li>8.135: 10 January 2010
643	<ul>
644
645	<li>All usage of static member methods inside Pythia8 has now been
646	eliminated. This simplifies for you to have several simultaneous
647	<code>Pythia</code> instances that are run with different conditions.
648	The three main classes affected by this are the <code>Settings</code>
649	and <code>ParticleData</code> databases and the <code>Rndm</code>
650	random-number generator. You can no longer address the methods of these
651	classes directly, but have to address them via the <code>settings</code>,
652	<code>particleData</code> and <code>rndm</code> instances in the
653	respective <code>Pythia</code> object. Also some other smaller pieces
654	of code are affected, e.g. Standard Model and SUSY couplings
655	(the latter in new files).
656	<br/><b>Note 1</b>: The documentation has been updated accordingly
657	on these webpages, but the "A Brief Introduction to PYTHIA 8.1"
658	still refers to the old behaviour of version 8.100.
659	<br/><b>Note 2</b>: the interface to the external LHAPDF library remains
660	static, since LHAPDF is written in Fortran and thus by definition
661	static.
662	<br/><b>Note 3:</b> if you want to have momentum smearing in
663	<code>CellJet</code> you now need to send in a pointer to a
664	random-number generator.
665	</li>
666
667	<li>Ten new proton PDF sets are made available internally:
668	MRST LO* (2007), MRST LO** (2008), MSTW 2008 LO (central member),
669	MSTW 2008 NLO (central member), CTEQ6L, CTEQ6L1, CTEQ6.6 (NLO,
670	central member), CT09MC1, CT09MC2, and CT09MCS, see
671	<?php $filepath = $_GET["filepath"];
672	echo "<a href='PDFSelection.php?filepath=".$filepath."' target='page'>";?>PDF Selection</a>. The Pomeron PDF data
673	files have been renamed for consistency. Thanks to Tomas Kasemets
674	for help with this [<a href="Bibliography.php" target="page">Kas10</a>].
675	</li>
676
677	<li>New parameters <code>TimeShower:pTmaxFudgeMPI</code> and
678	<code>SpaceShower:pTmaxFudgeMPI</code> introduced, to give the same
679	functionality for multiparton interactions that
680	<code>TimeShower:pTmaxFudge</code> and <code>SpaceShower:pTmaxFudge</code>
681	do for the hardest.</li>
682
683	<li>A few extensions of the <code>UserHooks</code> framework.
684	New methods <code>UserHooks:canVetoISREmission()</code> and
685	<code>UserHooks::doVetoISREmission(...)</code> allows the latest
686	initial-state emission to be studied before being finalized,
687	with the possibility to veto it.
688	Similarly <code>Userhooks:canVetoFSREmission()</code> and
689	<code>UserHooks::doVetoFSREmission(...)</code> can be used to
690	veto the latest final-state emission.</li>
691
692	<li>A number of loop counters have been introduced in the
693	<code>Info</code> class, that offers some further information on
694	the progress of the event generation, for use e.g. in conjunction
695	with the <code>UserHooks</code> facility.</li>
696
697	<li>The <code>Pythia::initTunes(...)</code> method is made public, so that
698	it can be called before the normal call from <code>Pythia::init(...)</code>.
699	That way it is possible to start out from a given tune and change a few
700	of the parameters.
701	</li>
702
703	<li>Bug corrected in <code>LHAFortran.h</code> for hard-process input
704	from Fortran commonblock. This did not work properly when the input
705	was used in combination with a second hard process generated internally.
706	Thanks to Mikhail Kirsanov and Roberto Chierici.
707
708	<li>Insertion of missing initialization of <code>isInit</code> in the
709	<code>Settings</code> and <code>ParticleData</code> constructors, and
710	<code>nInit</code> for <code>BeamParticle</code>.
711	Thanks to Leif Lönnblad.</li>
712
713	<li>Updated <code>Makefile.msc</code> for Windows users.</li>
714
715	<li>Fix of some non-optimal use of booleans, that give warnings on
716	a Windows compiler. Thanks to Anton Karneyeu.</li>
717
718	<li>New options for the <?php $filepath = $_GET["filepath"];
719	echo "<a href='SUSYLesHouchesAccord.php?filepath=".$filepath."' target='page'>";?>
720	SUSY Les Houches Accord</a> such that, by default,
721	particle and decay data are not overwritten for known Standard Model
722	particles (including <i>Z^0</i>, <i>W^+-</i> and <i>t</i>,
723	but excluding the Higgs).</li>
724
725	<li>Bug fix in <code>SusyLesHouches</code>, where the reading of SLHA
726	information embedded in an LHEF would not stop at the end of the header
727	section.</li>
728
729	<li>Bug correction for undefined secondary widths where decay products
730	together are heavier than the mother. Also unit default secondary width
731	values in the <code>DecayChannel</code> constructor.</li>
732
733	<li>Documentation updated, including change of current year to 2010.</li>
734
735	</ul>
736	</li>
737
738	<li>8.140: 16 July 2010
739	<ul>
740
741	<li>Four new draft <?php $filepath = $_GET["filepath"];
742	echo "<a href='Tunes.php?filepath=".$filepath."' target='page'>";?>tunes</a> available.</li>
743
744	<li>Introduction of a new scenario for production of Hidden-Valley
745	particles, and interleaved showering in the QCD and HV sectors, see
746	the new <?php $filepath = $_GET["filepath"];
747	echo "<a href='HiddenValleyProcesses.php?filepath=".$filepath."' target='page'>";?>Hidden Valleys</a>
748	description. A longer physics writeup is available [<a href="Bibliography.php" target="page">Car10</a>].
749	</li>
750
751	<li>Implementation of <i>2 -> 3</i> phase space selection intended
752	for QCD processes with massless partons. A new set of matching
753	<?php $filepath = $_GET["filepath"];
754	echo "<a href='PhaseSpaceCuts.php?filepath=".$filepath."' target='page'>";?>phase space cut parameters</a>.
755	The <?php $filepath = $_GET["filepath"];
756	echo "<a href='QCDProcesses.php?filepath=".$filepath."' target='page'>";?>ten different QCD <i>2 -> 3</i>
757	processes</a> have been implemented making use of this new
758	possibility, so far without a complete handling of possible colour
759	flows, however.</li>
760
761	<li>New processes have been added for
762	<?php $filepath = $_GET["filepath"];
763	echo "<a href='CompositenessProcesses.php?filepath=".$filepath."' target='page'>";?>contact interactions</a> in
764	<i>q q -> q q</i> and <i>q qbar -> q qbar</i> scattering.</li>
765
766	<li>A process has been added for TeV^-1 Sized
767	<?php $filepath = $_GET["filepath"];
768	echo "<a href='ExtraDimensionalProcesses.php?filepath=".$filepath."' target='page'>";?>Extra Dimensions</a>, which
769	involves the electroweak KK gauge bosons, i.e. <i>gamma_{KK}/Z_{KK}</i>,
770	in one TeV^-1 sized extra dimension; see <code>main30.cc</code> for
771	an example. This scenario is described in [<a href="Bibliography.php" target="page">Bel10</a>]. Thanks to
772	Noam Hod and coworkers for contributing this code.</li>
773
774	<li>In the Randall-Sundrum extra-dimensional scenario a new option has
775	been added where SM fields can exist in the bulk rather than only on
776	a brane. (Still under development.) Furthermore production of a
777	Kaluza-Klein gluon state has been added, and the <code> main28.cc</code>
778	test program extended.</li>
779
780	<li>The scenario for monojets in Large Extra Dimensions has been expanded
781	with an alternative for scalar graviton exchange instead of tensor one.
782	</li>
783
784	<li>New parameters for maximum scale of
785	<?php $filepath = $_GET["filepath"];
786	echo "<a href='TimelikeShowers.php?filepath=".$filepath."' target='page'>";?>timelike showers</a>,
787	<code>TimeShower:pTmaxMatch</code>, and the dampening of hard radiation,
788	<code>TimeShower:pTdampMatch</code> and <code>TimeShower:pTdampFudge</code>,
789	by analogy with corresponding ones for spacelike showers. Also new method
790	<code>TimeShower:limitPTmax(...)</code> to implement alternative procedures.
791	For dipoles stretched to the beam the new switch
792	<code>TimeShower:dampenBeamRecoil</code> allows to dampen radiation
793	close to the beam direction, with a changed default behaviour.</li>
794
795	<li>Azimuthal anisotropies from coherence arguments have been introduced
796	for the spacelike parton showers, see <code>SpaceShower:phiIntAsym</code>
797	and <code>SpaceShower:strengthIntAsym</code>.
798	Also azimuthal anisotropies from gluon polarization have been introduced
799	for the spacelike parton showers, see <code>SpaceShower:phiPolAsym</code>,
800	and updated for timelike parton showers, see
801	<code>TimeShower:phiPolAsym</code>.</li>
802
803	<li>Improvements for the matching to POWHEG LHEF-style input illustrated
804	by the new <code>main71.cc</code> example. See also [<a href="Bibliography.php" target="page">Cor10</a>].</li>
805
806	<li>A set of new processes <i>gamma gamma -> f fbar</i>, with <i>f</i>
807	quarks or leptons. Code for equivalent photon flux around an unresolved
808	proton, with more to come. Thanks to Oystein Alvestad.
809	</li>
810
811	<li>A new option has been included to dampen the growth of the diffractive
812	cross sections, see <?php $filepath = $_GET["filepath"];
813	echo "<a href='TotalCrossSections.php?filepath=".$filepath."' target='page'>";?>Total Cross
814	Sections</a>.</li>
815
816	<li>A new method <code>virtual int SigmaProcess::idSChannel()</code>
817	has been introduced. If overloaded to return a nonzero value then a
818	<i>2 -> n</i> process will appear listed as a <i>2 -> 1 -> n</i> one.
819	That is, an intermediate resonance with the requested identity will be
820	inserted in the event record, even without appearing in the calculation
821	of the matrix element proper. Thanks to Noam Hod for idea and code.</li>
822
823	<li>A new method <code>SigmaProcess::convertM2()</code> has been introduced
824	to optionally allow the <code>SigmaProcess::sigmaHat()</code> to return
825	the squared matrix element rather than <i>d(sigmaHat)/d(tHat)</i> for
826	<i> 2 -> 2 </i> processes. Furthermore kinematics is stored in the new
827	<code>mME</code> and <code>pME</code> vectors for alternative cross
828	section encodings.</li>
829
830	<li>Different encoding of the <i>f fbar -> Z W</i> cross section,
831	contributed by Merlin Kole, based on the cross section of
832	Brown, Sahdev and Mikaelian. Gives a distinctly different cross section
833	than the previous based on EHLQ (including their bug fix).
834	In particular the problem with negative cross sections is now fixed.</li>
835
836	<li>Minor updates: pass <code>xmlPath</code> to new MSTW and CTEQ PDFs;
837	reset beams earlier to give cleaner documentation.</li>
838
839	<li>The H1 Fit B LO parametrization to the Pomeron PDF has been included,
840	and made new default for Pomerons. Thanks to Paul Newman for providing
841	the data files.</li>
842
843	<li>Three changes, in principle unrelated, but with the common objective
844	to make the generation of a given event depend only on the values
845	determined during the initialization stage and on the state of the
846	random-number generator when the event is begun. The new default
847	should ensure a reproducible stop-and-restart behaviour, convenient
848	for debug purposes. Thanks to Michael Schmelling for stressing the
849	desire for such a behaviour.
850	<br/>(i) Introduction of a new option <code><?php $filepath = $_GET["filepath"];
851	echo "<a href='PhaseSpaceCuts.php?filepath=".$filepath."' target='page'>";?>
852	PhaseSpace:increaseMaximum</a></code> that allows to switch between
853	two strategies for handling the (hopefully rare) cases when the
854	assumed maximum of the cross section function is exceeded during the
855	event generation, with a changed default behaviour. In the old
856	default the maximum could be increased if it was exceeded during the run,
857	thereby introducing a memory of the previously generated events.
858	<br/>(ii) Updated handling of random numbers with Gaussian distributions.
859	The <code>gauss()</code> method now only generates one value at a time.
860	Instead the new <code>gauss2()</code> method returns a pair of Gauss
861	numbers, with related time savings. In the old approach one Gaussian
862	number could be buffered, which introduced a memory.
863	<br/>(iii) Minor bug fix in <code>MiniStringFragmentation</code>, where
864	the popcorn baryon state was not reset for each new system, again
865	giving a (flawed) memory.</li>
866
867	<li>New directory <code>rootexample</code> with a simple code example
868	how to use ROOT for histogramming in PYTHIA runs. See
869	<?php $filepath = $_GET["filepath"];
870	echo "<a href='ROOTusage.php?filepath=".$filepath."' target='page'>";?>ROOT Usage</a> for details. Thanks to Rene Brun.
871	</li>
872
873	<li>In the <code>HepMCinterface</code> the checks for unhadronized
874	quarks and gluons are not performed if hadronization has been switched
875	off.</li>
876
877	<li>The <code>UserHooks::initPtr(...)</code> has been expanded so that
878	pointers to more classes (beam particles, random number, couplings, etc.)
879	are sent in, thereby increasing the scope of possible user-written code.
880	Also, the <code>UserHooks::doVetoProcessLevel(Event& process)</code>
881	now allows the <code>process</code> event record to be modified,
882	even if it is not recommended. The new <code>Info::pTnow()</code>
883	method returns the current <i>pT</i> scale of the combined MPI, ISR
884	and FSR evolution, which can be useful for some user hooks decisions.
885	</li>
886
887	<li>Histograms of the <code>Hist</code> class can now be booked
888	with up to 1000 bins, instead of the previous maximum 100. All bins
889	can be written to file, but the line-printer style printing will join
890	nearby bins so at most 100 are printed, as before. </li>
891
892	<li>Updated <code>configure</code> and <code>Makefile</code>
893	to allow 64-bit compilation and more options. Thanks to Mikhail Kirsanov,
894	Rene Brun and Fons Rademakers.</li>
895
896	<li>Bug fix in <code>ProcessLevel</code> for colour flow checks of
897	junctions. Enables the decay of a neutralino to three quarks, e.g.
898	Thanks to Nils-Erik Bomark.</li>
899
900	<li>Bug fixes in <code>TimeShower</code>, where recoil partners in resonance
901	decays of coloured particles, and recoil partners in QED dipoles when beams
902	are not allowed to take a recoil, might not be correctly identified. </li>
903
904	<li>Bug fix in <code>SpaceShower</code>: when used with a fixed
905	<i>alpha_strong</i>, the threshold enhancement factor of
906	<i>g -> Q Qbar</i> became undefined. Thanks to Stefan Prestel.</li>
907
908	<li>Bug fix in initialization of resonance widths, where the
909	<code>minWidth</code> parameter could be used uninitialized,
910	occasionally resulting in strange initialization problems when
911	kinematics needs to force at least one resonance to be off-shell.</li>
912
913	<li>Minor updates of <code>main06.cc</code>, <code>main10.cc</code>
914	and <code>main23.cc</code>.</li>
915
916	<li>Bug fix in mother pointer of multiparton interactions in
917	diffractive systems.</li>
918
919	</ul>
920	</li>
921
922	<li>8.142: 15 August 2010
923	<ul>
924
925	<li>The strategy for setting up tune values has been changed.
926	Previously the <code>Tune:ee</code> and <code>Tune:pp</code>
927	settings were only interpreted during the
928	<code>Pythia::init(...)</code> stage. Now they are interpreted
929	as soon as they are read. Specifically this means that it is
930	possible to override any of the tune parameters by putting new
931	commands below <code>Tune:ee</code> and <code>Tune:pp</code>
932	in the <code>Pythia::readFile(...)</code> configuration file
933	or in the list of <code>Pythia::readString(...)</code> commands.
934	<br/>As a consequence of this change, the public
935	<code>Pythia::initTunes(...)</code> method has been replaced by
936	two private <code>Settings::initTuneEE(...)</code> and
937	<code>Settings::initTunePP(...)</code> methods.
938	<br/>If <code>Tune:ee</code> or <code>Tune:pp</code> are
939	nonvanishing by default, then the corresponding tune variables
940	are set also from the <code>Pythia</code> constructor, before any
941	user changes are possible. Currently this is not relevant.
942	</li>
943
944	<li>Bug fix in the setup of the <code>Tune:pp = 5</code> and
945	<code>= 6</code> options, which meant that diffractive cross
946	sections were not reduced as advertised.</li>
947
948	<li>The default value of <code>MultipartonInteractions:pT0Ref</code>
949	has been slightly reduced so as to give a somewhat improved
950	default description. It is not intended as a replacement for the
951	specific tunes, however.</li>
952
953	<li>Some comparisons between tunes and data, obtained with the
954	Rivet package, have been posted on
955	<a href="http://home.thep.lu.se/~richard/pythia81/">
956	http://home.thep.lu.se/~richard/pythia81/</a>.
957	Further improvements can be expected from future Professor-based
958	tunes. The current set of 2C, 2M, 3C and 3M "draft tunes" have
959	deliberately been chosen different also to explore a range of
960	possibilities. One not visible in the plots is the fraction
961	of single and double diffractive events in the inelastic cross
962	section. This is 32% in 2C and 2M, while it was reduced to
963	21% in 3C and 3M, and a recent ATLAS study (ATLAS-CONF-2010-048)
964	would suggest 28+-4%.</li>
965
966	<li>Minor changes in <code>TimeShower</code> and
967	<code>SpaceShower</code>, as protection if the <i>c</i> or
968	<i>b</i> masses are set small.</li>
969
970	<li>Bug fix in <code>SpaceShower</code>, for case when <i>phi</i>
971	angle selection is biased to take into account interference effects.
972	</li>
973
974	<li>The <code>SigmaProcess::convertM2()</code> method now has
975	been implemented also for <i>2 -> 1</i> processes, so that it is
976	possible to provide the squared matrix element instead of
977	<i>sigmaHat</i> for semi-internal processes. A fixed-width
978	Breit-Wigner is also inserted, since the matrix element is supposed
979	not to include it.</li>
980
981	<li>New method <code>SigmaProcess::setupForME()</code> does an
982	extended conversion from the internal kinematics to an almost
983	equivalent one, better adapted to the mass conventions of matrix-element
984	caclulation programs, such as massive incoming <i>b</i> quarks.
985	New flags allow to determine whether the <i>c</i>, <i>b</i>,
986	<i>mu</i> and <i>tau</i> should be considered massless or not
987	in the calculations.</li>
988
989	<li>Two new friend methods <code>table</code> of the <code>Hist</code>
990	class allow to print a table with three columns, the first for the
991	(common!) <i>x</i> values and the other two for the respective
992	histogram values. A new method <code>takeSqrt</code> for the square
993	root of histogram bin contents.
994	</li>
995
996	</ul>
997	</li>
998
999	<li>8.145: 10 November 2010
1000	<ul>
1001
1002	<li><code>Couplings</code> is defined in <code>StandardModel.h</code>
1003	as a derived class of <code>coupSM</code> and has only one extra flag:
1004	<code>isSUSY</code> to check presence of extra couplings.Changed all
1005	pointers <code>CoupSM</code> to <code>Couplings</code> and removed
1006	explicit references to <code>CoupSUSY*</code>. The <code>coupSUSY</code>
1007	object is only initialised if SUSY couplings are present. The new pointer
1008	<code>couplingsPtr</code> points either to only SM couplings or SM+SUSY
1009	couplings based on SLHA data.</li>
1010
1011	<li>New files <code>SusyResonanceWidths.h/cc</code> contains the
1012	<code>SusyResonanceWidths</code> class, which inherits from
1013	<code>ResonanceWidths</code> but typecasts the <code>couplingsPtr</code>
1014	to <code>(CoupSUSY*) coupSUSYPtr</code>. This is the base class for
1015	all SUSY resonances. It contains the <code>ResonanceSquark</code> class
1016	for all squark decays. A new flag <code>SLHA:useDecayTable</code>
1017	to check if internal widths should be overwritten by those read in
1018	via SLHA.</li>
1019
1020	<li>Added new functionality to <code>SusyLesHouches</code> for read-in
1021	of generic user blocks in the SLHA format, along with methods to
1022	extract parameters from them with typecasting controlled by the user.
1023	Intended for use with user-written semi-internal processes.</li>
1024
1025	<li>Added <code>Sigma1qq2antisquark</code> cross section.</li>
1026
1027	<li>Some new flags and modes in the <code>SUSY</code> and
1028	<code>SLHA</code> series offer further functionality.</li>
1029
1030	<li>Several further changes as a consequence of the upgrade of the SUSY
1031	machinery.</li>
1032
1033	<li>Bug/typo fixes in rotation matrices for SUSY couplings and for the
1034	processes <code>qqbar2squarkantisquark</code>,
1035	<code>qq2squarksquark</code> and more.</li>
1036
1037	<li>Improved handling of colour junctions. Added new example program
1038	<code>main72.cc</code>, to illustrate read-in of color junction
1039	structures via LHEF (<code>main72.lhe</code>). The example used is SUSY
1040	with RPV.</li>
1041
1042	<li>New Tune 4C introduced as <code>Tune:pp = 5</code>. The more crude
1043	(non-)tunes 3C and 3M are removed.</li>
1044
1045	<li>New methods <code>Settings::getFlagMap(...)</code>,
1046	<code>Settings::getModeMap(...)</code>,
1047	<code>Settings::getParmMap(...)</code> and
1048	<code>Settings::getWordMap(...)</code> allows to return a map of all
1049	settings of the respective type that contain a specific string
1050	in its name.
1051	</li>
1052
1053	<li>Improved description of excited <i>g^/KK-gluon^</i> production
1054	in the <code>Sigma1qqbar2KKgluonStar</code> and
1055	<code>ResonanceKKgluon</code> classes.</li>
1056
1057	<li>Possibility added to let Hidden-Valley <i>gamma_v</i> have
1058	a nonero mass and decay by mixing with the ordinary photon.
1059	Still experimental.</li>
1060
1061	<li>Minor bug fix in handling of three-body phase space.</li>
1062
1063	<li>Minor correction in <code>Sigma2ffbar2TEVffbar</code> class.</li>
1064
1065	<li>Bug fix for decays of <i>W'</i> to a pair of heavy fermions when
1066	<i>gV != gA</i>. Thanks to M. Chizhov, see arXiv:0705.3944. </li>
1067
1068	<li>Restore the older EHLQ-based encoding of the <i>f fbar -> Z W</i>
1069	cross section, which was changed in version 8.140, since comparisons
1070	with Madgraph gives much better agreement with it than with the
1071	expression of Brown, Sahdev and Mikaelian.</li>
1072
1073	<li>The <code>HepMCInterface</code> now also stores colour flow
1074	information for coloured particles.</li>
1075
1076	<li>Pointer to <code>Couplings</code> made available for particle
1077	decays.</li>
1078
1079	<li>Minor update in <code>main61.cc</code> for more elegant usage
1080	of FastJet, as suggested by Gregory Soyez.</li>
1081
1082	</ul>
1083	</li>
1084
1085	<li>8.150: 20 April 2011
1086	<ul>
1087
1088	<li>Tune 4C is made default. It is based on first comparisons with
1089	LHC data [<a href="Bibliography.php" target="page">Cor10a</a>], and has also been checked independently
1090	[<a href="Bibliography.php" target="page">Buc11</a>] to give reasonable agreement with many distributions.
1091	</li>
1092
1093	<li>The description of <i>tau</i> lepton decays has been significantly
1094	enhanced, to include helicity information related to the production
1095	process and hadronic currents fitted to data. A complete writeup is
1096	in preparation [<a href="Bibliography.php" target="page">Ilt11</a>]. A new flag is introduced to revert
1097	to the old behaviour, for cross-checks, see
1098	<?php $filepath = $_GET["filepath"];
1099	echo "<a href='ParticleDecays.php?filepath=".$filepath."' target='page'>";?>Particle Decays</a>.
1100	The new tau decay machinery is on by default.
1101	</li>
1102
1103	<li>A new option <code>MultipartonInteractions:bProfile = 4</code> has
1104	been introduced for the impact-parameter profile of protons in the
1105	<?php $filepath = $_GET["filepath"];
1106	echo "<a href='MultipartonInteractions.php?filepath=".$filepath."' target='page'>";?>Multiparton Interactions</a>
1107	framework, wherein low-<i>x</i> partons are spread over a larger area
1108	than high-<i>x</i> ones, see [<a href="Bibliography.php" target="page">Cor11</a>]. A new method
1109	<code>Info::eMPI(i)</code> gives back the enhancement factor related to
1110	the <code>i</code>'th interaction. The impact-parameter profile can now
1111	be selected separately for <?php $filepath = $_GET["filepath"];
1112	echo "<a href='Diffraction.php?filepath=".$filepath."' target='page'>";?>diffraction</a>,
1113	but without a <code>bProfile = 4</code> option.
1114	</li>
1115
1116	<li>The possibility of "hadronization" in the
1117	<?php $filepath = $_GET["filepath"];
1118	echo "<a href='HiddenValleyProcesses.php?filepath=".$filepath."' target='page'>";?>Hidden Valley</a> sector
1119	has been added as a new option <code>HiddenValley:fragment = on</code>.
1120	This is based on a copy of the standard string fragmentation framework,
1121	but with the option of a completely separate "flavour" sector, and
1122	separately tunable longitudinal fragmentation functions and transverse
1123	momenta. For now only a simple flavour scenario is provided, where
1124	flavour-diagonal mesons can decay back into the normal visible sector
1125	while off-diagonal ones remain hidden. A writeup of the model is in
1126	preparation [<a href="Bibliography.php" target="page">Car11</a>]. Also some further Hidden Valley options
1127	have been added.</li>
1128
1129	<li>Included possibility in <code>TimeShower</code> for QCD dipoles to
1130	have an adjustible normalization factor, via the new
1131	<code>bool isFlexible</code> and <code>double flexFactor</code>
1132	properties of <code>class TimeDipoleEnd</code>. This flexibility is used
1133	to treat radiation off colour topologies with epsilon tensors, in
1134	particular colour junctions which have all their partons in the
1135	final state. (An example is the BNV-SUSY decay ~chi0→uds.) For
1136	such topologies, the new treatment in PYTHIA 8 is that a
1137	half-strength dipole is spanned between all combinations of
1138	final-state quarks. For junctions with an incoming (anti)colour line (such
1139	as in the BNV-SUSY decay ~t*→cb), a full-strength dipole is
1140	instead spanned between the two daughters, with no radiation from the
1141	decaying object (in its CM). As will be described in a fortcoming
1142	paper with N. Desai, this should give the
1143	closest possible correspondence to the radiation patterns exhibited
1144	by higher-order matrix elements for this type of process.</li>
1145
1146	<li>Corrected harmless bugs in <code>ProcessLevel::findJunctions</code>
1147	which caused junctions of types 3 and 4 (i.e., junctions with 1
1148	incoming color tag) to sometimes be incorrectly classified as types
1149	1 and 2 (with all color tags outgoing), respectively.
1150	Since the parity (even/odd) of the junction kind was still correct,
1151	however, this did not cause any problems at the hadronization
1152	stage.</li>
1153
1154	<li>The junction-finder in <code>ProcessLevel::findJunctions</code>
1155	has been made more stable, and the following ordering of the color
1156	tags returned by <code>Event::endColJunction(iJun, iLeg)</code> is
1157	now enforced: for junction kinds 3 and 4 (one tag
1158	incoming), <code>iLeg = 0</code> will return the
1159	incoming tag, while for kinds 5 and 6 (two tags incoming),
1160	<code>iLeg = 0</code> and <code>iLeg = 1</code> will return the
1161	incoming tags. Apart from this ordering, the color tags are
1162	ordered in ascending color tag number.</li>
1163
1164	<li>Declarations of friend functions moved to sit outside the class
1165	it befriends. Thanks to Axel Naumann for pointing out the incorrect
1166	previous construction.</li>
1167
1168	<li>The <code>rootexample</code> subdirectory becomes
1169	<code>rootexamples</code> as the old example is split into two,
1170	with improved documentation to clarify usage. Thanks to Axel Naumann
1171	and Bernhard Meirose for the new code.</li>
1172
1173	<li>In the Les Houches Event File machinery, input type has been
1174	changed from <code>ifstream</code> to <code>istream</code> for more
1175	flexibility.</li>
1176
1177	<li>R-hadron handling is largely implemented, see the
1178	<?php $filepath = $_GET["filepath"];
1179	echo "<a href='RHadrons.php?filepath=".$filepath."' target='page'>";?>R-hadrons</a> page, although some aspects
1180	still need polishing. A new class <code>RHadrons</code> takes
1181	care of the hadronization and decay. Particle data have been added
1182	for R-hadrons containing a gluino, stop or sbottom, but could
1183	alternatively be used for other long-lived coloured particles.
1184	Thanks to Bernhard Meirose for support.
1185	</li>
1186
1187	<li>Calculations of SUSY decay widths included by
1188	N. Desai, contained in the new source
1189	files <code>SusyResonanceWidth.cc</code>
1190	and </code>.h</code>. Validation and addition of more modes is still in
1191	progress, so this implementation should be considered preliminary
1192	for now. For a list of available modes, see
1193	the <?php $filepath = $_GET["filepath"];
1194	echo "<a href='SUSYProcesses.php?filepath=".$filepath."' target='page'>";?>SUSY Processes</a> page.
1195	</li>
1196
1197	<li>A first implementation of the SLHA-based QNUMBERS interface for
1198	defining new exotic particles has been
1199	included. See [<a href="Bibliography.php" target="page">Alw07</a>] and
1200	the <?php $filepath = $_GET["filepath"];
1201	echo "<a href='SUSYLesHouchesAccord.php?filepath=".$filepath."' target='page'>";?>SUSY Les Houches Accord</a>
1202	page. </li>
1203
1204	<li>Read-in of LHEF events containing Baryon Number Violating vertices
1205	has been included, using colour junctions, see
1206	the <?php $filepath = $_GET["filepath"];
1207	echo "<a href='EventRecord.php?filepath=".$filepath."' target='page'>";?>Event Record</a> page. The advanced
1208	shower model taking into account the full colour structure of such
1209	events, developed by N. Desai and described above,
1210	is turned on by default in such events.
1211	Several test cases were used to
1212	validate this implementation, but it is possible that problems could
1213	still exist for some cases. Feedback is welcome. Thanks to
1214	the MadGraph authors for providing several test cases.</li>
1215
1216	<li>Some first steps taken to allow events containing colour sextets,
1217	e.g., from semi-internal processes or LHEF interfaces, and/or from
1218	SLHA <code>DECAY</code> tables. New
1219	<code>colType</code> codes 3 and -3 are introduced to describe
1220	sextets and antisextets, respectively. The state of the current
1221	implementation is that hard processes containing such states can be
1222	read in and decays generated (via <code>DECAY</code> tables). Parton
1223	showers can be added, but the sextets themselves do not, as yet,
1224	shower, and any undecayed sextets remaining at the hadronization
1225	stage would lead to unpredictable problems if hadronization is
1226	switched on. Thanks to J. Alwall for help with testing
1227	this implementation.
1228	</li>
1229
1230	<li>The functionality of the SLHA SUSY/BSM interface (see
1231	the <?php $filepath = $_GET["filepath"];
1232	echo "<a href='SUSYLesHouches.php?filepath=".$filepath."' target='page'>";?>SUSY Les Houches</a> page) has been
1233	extended so that copies of all <code>BLOCK</code>s are now stored
1234	internally as
1235	strings, regardless of whether they correspond to "official" SLHA
1236	blocks or not. Their contents can subsequently be queried by a set
1237	of new templated member functions of the
1238	class <code>SusyLesHouches</code>. Available query functions so far
1239	include
1240	<br/><code>template <class T> bool getEntry(string, T&);</code>,
1241	<br/><code>template <class T> bool getEntry(string, int, T&);</code>,
1242	<br/><code>template <class T> bool getEntry(string, int, int, T&);
1243	</code>, and
1244	<br/><code>template <class T> bool getEntry(string, int,
1245	int, int, T&);</code>,
1246	<br/>where the type of
1247	the argument used in the call determines how to read the block
1248	entries. Thus, if an LHEF, SLHA, or other card file is read in by
1249	PYTHIA, the contents of any <code>BLOCK</code> in that file can
1250	subsequently be queried run-time using these functions. This is
1251	used, e.g., in the new interface between MADGRAPH 5 and PYTHIA
1252	8. Thanks to the MADGRAPH team, and to J. Alwall in particular, for
1253	help and debug on this new implementation.
1254	</li>
1255
1256	</ul>
1257	</li>
1258
1259	<li>8.153: 10 August 2011
1260	<ul>
1261
1262	<li>The setup of tunes has been modified, see the
1263	<?php $filepath = $_GET["filepath"];
1264	echo "<a href='Tunes.php?filepath=".$filepath."' target='page'>";?>Tunes</a> page for details. Specifically
1265	the <code>Tune:ee</code> and <code>Tune:pp</code> modes have
1266	acquired a new option <code>-1</code> for a forced restore to the
1267	default values of all settings used in the respective kind of
1268	tunes.</li>
1269
1270	<li>The code for handling multiparton interactions in the scenario with
1271	an <i>x</i>-dependent width of the Gaussian matter profile
1272	[<a href="Bibliography.php" target="page">Cor11</a>], has been improved and updated. Tune 4Cx, which
1273	is based on this option, has been added as a further tune option.</li>
1274
1275	<li>A possibility to bias the phase-space selection has been added,
1276	whereby some phase space regions can be oversampled, which is
1277	compensated by assigning a weight to each event.
1278	A new set of methods have been added to the <code>UserHooks</code>
1279	class to allow users to program how to bias the selection.</li>
1280
1281	<li>New options added so that matrix-element corrections can be
1282	switched off after the first branching in ISR or FSR.</li>
1283
1284	<li>Some new <code>Info</code> methods have been added to store
1285	information on latest ISR branching. The <code>SpaceShower</code>
1286	class has also been corrected so that the latest <i>z = 1/2</i>
1287	when not defined by history. This avoids undefined values for
1288	azimuthal asymmetries. Thanks to Stefan Prestel for finding and
1289	sorting out this problem.</li>
1290
1291	<li>The <code>Pythia::forceHadronLevel()</code> method now takes
1292	an argument that optionally means that existing junction information
1293	is not overwritten. Thanks to Leif Lönnblad for pointing out
1294	the usefulness of this.</li>
1295
1296	<li>For particle decays to a varying number of hadrons the multiplicity
1297	increase with mass has been somewhat reduced, and especially for
1298	<code>meMode = 23</code> a separate even slower increase has been
1299	introduced.</li>
1300
1301	<li>New possibility to force the tau polarization.</li>
1302
1303	<li>Bug fix for the special case in which events containing SUSY
1304	particles are generated without proper initialization of SUSY decays.
1305	This can happen, e.g., if events containing SUSY particles are read
1306	in via external LHEF files, if those files do not contain readable
1307	SLHA spectra in their headers. In this case, a failed attempt to
1308	generate sparticle decays with ill-defined couplings previously
1309	led to crashes. The program now reverts to the old behaviour,
1310	based on static decay tables, in such cases, with the default
1311	being to decay all sparticles to gravitino + particle. An error
1312	message stating that the full SUSY treatment has been switched
1313	off and why is also issued. Thanks to N. Desai for this fix.</li>
1314
1315	<li>The R-hadron machinery has been completed.</li>
1316
1317	<li>Minor change in timelike showers: gluons which fall below the
1318	<i>pTmin</i> cutoff by the correction for mass effects are now
1319	eliminated, while previously they were kept. This reduces the
1320	number of gluons somewhat, but has no significant effects on the
1321	hadronic final state. (Prompted by R-hadron studies, where big mass
1322	effects else give bothersome low-energy gluons.)</li>
1323
1324	<li>Corrected typos in two of the Upsilon wave function matrix
1325	elements, <code>Bottomonium:OUpsilon3P08</code> and
1326	<code>Bottomonium:Ochib03P01</code>. Thanks to Beate Heinemann for
1327	pointing it out.</li>
1328
1329	<li>Implemented <i>f</i> decay angle in <i>f f -> f f</i> processes,
1330	and fixed some bugs for the same process. Thanks to Piyali Banerjee
1331	for tests.</li>
1332
1333	<li>Introduce possibility to separate production channels for
1334	TeV-sized extra dimensions, and a small code correction. Thanks to
1335	Noam Hod for code contribution.</li>
1336
1337	<li>Bug fix for neutrino beams: since neutrinos are always lefthanded
1338	there should be a factor 2 in the cross section, relative to charged
1339	leptons, from the non-need to average over incoming spin states. This
1340	is now fixed by introducing a new PDF class <code>NeutrinoPoint</code>
1341	for (unresolved) neutrinos, with normalization 2 rather than 1 for
1342	charged leptons. Thanks to Ryosuke Sato.</li>
1343
1344	<li>Bug fix for some (rarely used) particle settings, which could not
1345	be changed by users because they were read too early. Thanks to
1346	Andrew Altheimer and Gustaaf Brooijmans.</li>
1347
1348	<li>Bug fix in handling of <code>tau</code> decays, where setting of
1349	decay vertices could write outside memory. Thanks to Steven Schramm.</li>
1350
1351	<li>Minor expansion of the <code>BeamParticle</code> constructor.</li>
1352
1353	<li>Minor bug fix in CTEQ 6L for uninitialized variables.</li>
1354
1355	<li>Minor bug fix in fragmentation flavour combination to hadron.</li>
1356
1357	<li>Some updates of the documentation, including new pages on
1358	MadGraph 5 as a generator for semi-internal processes (thanks to
1359	Johan Alwall) and on RIVET interfacing.</li>
1360
1361	<li>Minor improvements of ROOT- and HepMC-related code and documentation.</li>
1362
1363	<li>Some cleanup of code.</li>
1364
1365	</ul>
1366	</li>
1367
1368	<li>8.157: 10 November 2011
1369	<ul>
1370
1371	<ii>StefanPrestel joins as new member of the PYTHIA author team.
1372	He is mainly working on matching/merging issues, and has contributed
1373	the CKKW-L machinery mentioned below.</li>
1374
1375	<li>Merging capabilities according to the CKKW-L scheme [<a href="Bibliography.php" target="page">Lon11</a>]
1376	have been added, see the new
1377	<?php $filepath = $_GET["filepath"];
1378	echo "<a href='MatrixElementMerging.php?filepath=".$filepath."' target='page'>";?>Matrix Element Merging</a>
1379	page. It involves new classes to reconstruct and select how a
1380	matrix-element-generated partonic configuration could have been obtained
1381	by the PYTHIA evolution, and to perform trial showers (using a new
1382	copy of the normal parton-level machinery) that introduce the appropriate
1383	Sudakov suppression factors. New examples to illustrate various
1384	common tasks are found in <code>main81.cc</code>, <code>main82.cc</code>,
1385	<code>main83.cc</code> and <code>main84.cc</code>.</li>
1386
1387	<li>The <code>main71.cc</code> program is now generalised for reading
1388	in arbitrary POWHEG LHE files, to implement a smooth matching between NLO
1389	matrix elements and the PYTHIA parton showers. Cuts are made on both
1390	ISR and FSR emissions, while previously only ISR was covered. The key
1391	assumptions are the <i>pT</i> definitions used for ISR and FSR, but several
1392	further options are available, as documented in the <code>main71.cmnd</code>
1393	file. Work is still ongoing to pick the best default options. </li>
1394
1395	<li>Several expansions of the <code>UserHooks</code> class.
1396	For both <code>doVetoFSREmission</code> and <code>doVetoISREmission</code>
1397	a new argument <code>iSys</code> labels the system within which the
1398	radiation occurs. For <code>doVetoFSREmission</code> a further argument
1399	<code>inResonance</code> distinguishes FSR in resonance
1400	decays from that in the hard process itself. New methods
1401	<code>canVetoMPIEmission</code> and <code>doVetoMPIEmission</code>
1402	have been added to veto multiparton interactions in the same way as
1403	FSR and ISR. In <code>biasSelectionBy</code> at times incorrect values
1404	for <code>inEvent</code> has been corrected. Also some systematization
1405	of the use of <code>const</code>.</li>
1406
1407	<li>A new model for hadron scattering is introduced, still at an early
1408	stage and therefore more intended for internal development than for the
1409	normal user. The basic idea is that a high-energy <i>pp</i> collision
1410	involves the fragmentation of multiparton strings that overlap in space
1411	(and time). Also the produced hadrons therefore initially overlap, and
1412	there is a strong likelihood that hadrons can scatter against each other
1413	until the system has expanded sufficiently. This can e.g. increase the
1414	transverse momentum of heavier hadrons at the expense of lighter ones.
1415	</li>
1416
1417	<li>A new jet finder <code>SlowJet</code> offers simple access to the
1418	inclusive <i>kT</i>, anti-<i>kT</i>, and Cambridge/Aachen
1419	algorithms in a cylindrical coordinate frame. The jet reconstruction
1420	is then based on sequential recombination with progressive removal,
1421	using the <i>E</i> recombination scheme. The minimalistic
1422	<code>SlowJet</code> code is much slower than <code>FastJet</code>
1423	[<a href="Bibliography.php" target="page">Cac06</a>], and contains less options, but reconstructs the same
1424	jets if run under identical conditions. For details see the
1425	<?php $filepath = $_GET["filepath"];
1426	echo "<a href='EventAnalysis.php?filepath=".$filepath."' target='page'>";?>Event Analysis</a> page.</li>
1427
1428	<li>Starting in gcc 4.6, it is possible to switch off specific warnings
1429	around specific blocks of code. Although version 4.6 is some way off
1430	from being commonly found, this option has now been introduced to switch
1431	off <code>-Wshadow</code> warnings in <code>HepMCInterface.cc</code>.
1432	For other compilers, or earlier versions of gcc, the old behaviour
1433	is retained.</li>
1434
1435	<li>Support for reading in gzipped LHEFs has been added in the
1436	<code>LesHouches</code> and <code>SusyLesHouches</code> classes.
1437	This also affects <code>configure</code> and <code>Makefile</code>s.
1438	Unless explicitly enabled, it should not affect anything.
1439	If enabled, it relies on the Boost and zlib libraries to function,
1440	so paths to these must be set appropriately, see the
1441	<code>README</code> file for details. The Boost header files can
1442	give very many shadow warnings, so <code>-Wshadow</code> is disabled
1443	if gzip support is enabled, as described above.</li>
1444
1445	<li>Introduce use of the <code>HEPMC_HAS_UNITS</code> environment
1446	variable in the <code>HepMCInterface.cc</code> and <code>main32.cc</code>
1447	codes to automatically check whether GeV and mm can be set as relevant
1448	units. If yes, then it is set in <code>main32.cc</code>. If no,
1449	a conversion from GeV to MeV is done explicitly in
1450	<code>HepMCInterface.cc</code>. Note that, for early HepMC versions,
1451	this means a change of behaviour. Thanks to Andy Buckley.</li>
1452
1453	<li>A new method <code>Info::lhaStrategy()</code> returns the
1454	Les Houches event weighting strategy where relevant, and 0 where not.
1455	For the strategies <i>+-4</i> the event weight and sum,
1456	<code>Info::weight()</code> and <code>Info::weightSum()</code>,
1457	is now in units of pb at output, as it should be at input.
1458	(While internally mb is used.)</li>
1459
1460	<li>New flag <code>Check:abortIfVeto</code> allows the user to
1461	resume control over execution in case of a veto in the event
1462	generation process.</li>
1463
1464	<li>New method <code>Event::at(i)</code> returns reference to
1465	<code>i</code>'th particle in the event record.</li>
1466
1467	<li>Introduce the Fermi constant as one of the Standard Model
1468	parameters.</li>
1469
1470	<li>Included automatic pre-initialization of SLHA blocks MASS and
1471	SMINPUTS using PYTHIA's SM parameters and particle data table
1472	values.</li>
1473
1474	<li>SUSY: added sleptons (and sneutrinos) as resonances.
1475	Corrected 2-body decay widths of gluinos, squarks and gauginos.
1476	Added sleptonic decay modes to gaugino decays.
1477	Implemented 2-body decays of sleptons (and sneutrinos)
1478	into sleptons/leptons/gauginos. Corrected slepton couplings (they
1479	now look exactly like squark couplings, using a 6x6 slepton mixing
1480	matrix).</li>
1481
1482	<li>New parameter <code>Diffraction:probMaxPert</code> introduce to
1483	give more flexibility in transition from a nonperturbative to a
1484	perturbative description of a diffractive system.</li>
1485
1486	<li>Bug corrected in <code>SigmaEW.cc</code>, for the process
1487	<code>WeakSingleBoson:ffbar2ffbar(s:gm)</code>. Previously, all outgoing
1488	quark flavours in this process were erroneously assigned ID code 5
1489	(b quarks). This has now been corrected so the proper ratios are
1490	obtained, with <i>u : c : d : s : b = 4 : 4 : 1 : 1 : 1</i>,
1491	according to the squared quark charges.</li>
1492
1493	<li>Changes in <code>FragmentationSystems</code> and
1494	<code>StringFragmentation</code> to reject systems with three or more
1495	interconnected junctions. This may happen in baryon-number-violating
1496	scenarios in pp collisions, if both of the beam baryon junctions are
1497	resolved and get connected via an antijunction created by a
1498	hard-process BNV vertex. In principle, this could be addressed by an
1499	extension of the existing junction fragmentation framework. However,
1500	since it happens rarely, for the time being an error message is printed
1501	and the fragmentation restarted.
1502	</li>
1503
1504	<li>Change in <code>Event::copy</code> to safeguard against attempting
1505	to copy out-of-range entries. An attempt to copy a non-existing entry
1506	will now return -1.</li>
1507
1508	<li>Bug fix in the machinery for the user to force the setting of
1509	tau polarization.</li>
1510
1511	<li>Bug fix in the initial search for a maximum of the process
1512	cross section (only affecting rare cases).</li>
1513
1514	<li>Corrected angular decay distributions for two compositeness
1515	processes, <code>Sigma2qq2qStarq</code> and
1516	<code>Sigma2qqbar2lStarlbar</code>.</li>
1517
1518	<li>Extra check in <code>HiddenValleyFragmentation</code> to make sure
1519	that pointers which have not been assigned with <code>new</code> are not
1520	deleted.</li>
1521
1522	<li>Some further minor changes.</li>
1523
1524	</ul>
1525	</li>
1526
1527	<li>8.160: 23 January 2012
1528	<ul>
1529
1530	<li>The older term "multiple interactions" has been replaced by the
1531	new standard "multiparton interactions" one, and correspondingly the
1532	abbreviation MI by MPI. This affects everything: settings, class and
1533	method names, documentation, etc. It therefore becomes necessary to
1534	rewrite user code. However, so as to keep the immediate effort at a
1535	reasonable level, the old settings names are kept as aliases. Thus
1536	<code>PartonLevel:MI</code> and <code>PartonLevel:MPI</code> are
1537	equivalent, and similarly <code>MultipleInteractions:pT0Ref</code>
1538	and <code>MultipartonInteractions:pT0Ref</code>. Should you be using
1539	methods such as <code>double Info::pTMI(int i)</code> you need to
1540	edit the code, however. All the <code>example/main*</code> files
1541	have been uopdated accordingly.</li>
1542
1543	<li>A new option <code>Beams:frameType = 5</code> has been added
1544	for the case where an external generator should provide LHA process
1545	information. The new <code>Pythia::setLHAupPtr(...)</code> method
1546	should then be used to link in this generator. The new switch
1547	<code>Beams:newLHEFsameInit</code> can be used to tell that a new
1548	LHEF should be used, but without the need for a new initialization.
1549	With these two changes, all the different ways of initializing
1550	can be covered by the <code>Pythia::init()</code> call with no
1551	arguments. The various <code>init(...)</code>options with arguments
1552	are deprecated and will be removed for PYTHIA 8.2.</li>
1553
1554	<li> The <code>Pythia::stat()</code> method, with no arguments,
1555	replaces <code>Pythia::statistics(...)</code>, although the latter
1556	remains as a deprecated alternative.</li>
1557
1558	<li>New settings <code>Init:...</code>, <code>Next:...</code>,
1559	and <code>Stat:...</code> can be used to steer some details of
1560	the operation of the <code>Pythia::init()</code>,
1561	<code>Pythia::next()</code> and <code>Pythia::stat()</code>,
1562	respectively. In particular it affects the amount of printout
1563	at the various stages of operation. See
1564	<?php $filepath = $_GET["filepath"];
1565	echo "<a href='MainProgramSettings.php?filepath=".$filepath."' target='page'>";?>here</a> for further details.
1566	This change involves several code changes, but in documentation
1567	rather than physics. Most of the <code>Main:...</code> settings
1568	are deprecated as a consequence.</li>
1569
1570	<li>The sample main programs in the <code>examples</code> subdirectory
1571	have been updated. This includes a change to the new favoured
1572	methods and settings outlined above, plus some update of the
1573	physics contents. Some of the examples have been combined,
1574	some others have been added (e.g. for R-hadroms), and as a consequence
1575	some renumbering has been made. See the modified list of
1576	<?php $filepath = $_GET["filepath"];
1577	echo "<a href='SampleMainPrograms.php?filepath=".$filepath."' target='page'>";?>sample main programs</a> for
1578	the new status. In particular note that (the new) <code>main61.cc</code>
1579	allows streamlined input and output in HepMC, like <code>main42.cc</code>
1580	(previously <code>main32.cc</code>), but additionally links to LHAPDF. </li>
1581
1582	<li>The <code>examples/configure</code> script has new optional argument
1583	<code>--with-pythia8</code>. It can be used to set the new
1584	<code>PYTHIA8LOCATION</code> environment variable, which then is used
1585	in <code>examples/Makefile</code> to give the path to the PYTHIA
1586	library. Thereby it becomes possible to relocate (parts of) the
1587	<code>examples</code> directory and still obtain the correct path.
1588	Thanks to Mikhail Kirsanov.</li>
1589
1590	<li>Polarization information has been included as a new
1591	<code>Particle</code> property, that can be set by
1592	<code>void pol(double polIn)</code> and obtained by
1593	<code>double pol()</code>. Default value is <code>9.</code>,
1594	in agreement with the Les Houches standard. Event listings have
1595	been expanded to optionally display this information. Currently
1596	polarization is not used internally.</li>
1597
1598	<li>The matrix element merging machinery has been modified as follows.
1599	<br/>- Improved handling of the hard process, so that MadGraph5-produced
1600	LHE files do not produce problems (sometimes, the choices of MG4 on what
1601	to put into a LHEF have changed in MG5).
1602	<br/>- Improved handling of colour for easier handling of states with
1603	many quarks (the code has been tested for states with up to 5
1604	<i>q qbar</i> pairs and some gluons).
1605	<br/>- Improved checking which clusterings are allowed. Now, clusterings
1606	should immediately be rejected if they lead to unphysical states,
1607	without the need to explicitly construct these states. This was needed
1608	to get <i>t tbar</i> production, VBF and some simple SUSY processes
1609	running with reasonable generality.
1610	<br/>- Improved handling of incomplete histories. Now there is an
1611	additional switch allowing code to try to swap some colours when fewer
1612	clusterings than requested have been found.
1613	</li>
1614
1615	<li>Updates in the handling of graviton resonances in scenarios with
1616	extra dimensions.
1617	<br/>- Now all G decays have correct angular distribution, which was not
1618	the case before for W/Z decays.
1619	<br/>- Added the possibility for G to only couple to longitudinal
1620	W/Z bosons, which affects both the width and angular distributions.
1621	<br/>- Added decays to Higgs pairs, <i>G -> hh</i>.
1622	</li>
1623
1624	<li>Bug fix in the <code>findJunctions()</code> function in
1625	<code>ProcessLevel.cc</code>. Changes introduced in version
1626	8.145 (to allow for junctions in baryon-number-violating
1627	processes) did not correctly handle the remapping of color
1628	tags that can be applied when adding beam remnants to events with
1629	multiparton interactions. A simpler and more stable algorithm is
1630	now applied for the simplest cases, with the more complex one only
1631	invoked for cases such as BNV, which are normally considered before
1632	remnants are added, hence avoiding this particular problem. Also some
1633	other changes in the handling of junction, including a safeguard to
1634	reject systems with three or more interconnected junctions.</li>
1635
1636	<li>Bug fix and updates to the SLHA interface. Possibility of infinite
1637	loop during <code>ProcessLevel::initSLHA</code> corrected. Modifications
1638	to <code>SusyLesHouches</code> to allow interpretation of SLHA1 spectra
1639	with R-parity violation. Rather than reject spectra that do not conform
1640	fully to the SLHA2 standard for RPV, the interface will now first look
1641	for SLHA1 mixing matrices and attempt to translate those into SLHA2 ones
1642	if possible. In this case, warnings that the expected SLHA2 blocks were
1643	not found will be printed. It is up to the user to check that the
1644	derived SLHA2 information is correct. Corresponding additions to
1645	<code>SusyCouplings.cc</code> to extract mixing-matrix information
1646	from the relevant SLHA2 RPV blocks when RPV is switched on.</li>
1647
1648	<li>Updated SLHA example <code>main24.cmnd</code> to use new example
1649	spectrum, <code>cmssm.spc</code>, corresponding to CMSSM point
1650	10.1.1, obtained with SOFTSUSY 3.3.0. Thanks to B. Allanach for
1651	providing the new spectrum file.</li>
1652
1653	<li>A new <code>include/FastJet3.h</code> header file simplifies
1654	interfacing of FastJet to Pythia. For details see documentation in
1655	the file itself. Thanks to Gavin Salam for this contribution.</li>
1656
1657	<li>The handling of diffraction has been made more flexible.
1658	Specifically the "total" Pomeron-proton cross section can now be made
1659	to depend on the mass of the diffractive system. This does not affect
1660	the diffractive cross section in pp collisions, which is set separately,
1661	but is used in the MPI machinery to affect the average number of
1662	interactions per Pomeron-proton collision. Furthermore, the allowed
1663	range for some parameters has been expanded. Thanks to Robert
1664	Ciesielski.</li>
1665
1666	<li>New method <code>Pythia::forceTimeShower(...)</code> can be used to
1667	generate a single final-state cascade from a set of partons, without
1668	any knowledge of prior history. This is mainly intended for toy studies.
1669	The meaning of the <code>ProcessLevel:all</code> switch has been modified
1670	so that this parton-level function is available, but not any others
1671	at this level.
1672	</li>
1673
1674	<li>ATLAS tune A2 now included. Thanks to Deepak Kar for
1675	providing it.</li>
1676
1677	<li>Change in the handling of recoils of timelike showers in resonance
1678	decays, in cases of coloured resonances such as <i>t -> b W</i>. In
1679	the first step the <i>W</i> always acts as recoiler to the <i>b</i>,
1680	but in subsequent step previously the <i>W</i> remained as recoiler to
1681	one dipole, while now all QCD-radiating partons recoil against another
1682	coloured parton. The old behaviour could give a (small) unphysical spike
1683	of radition collinear with the colourless recoiler in the subsequent
1684	emissions (while the pattern of the first was and remains correct).
1685	The old behaviour can be recovered for checks, see
1686	<code>TimeShower:recoilToColoured</code>.
1687	Thanks to Yevgeny Kats for pointing out this issue (previously noted
1688	for Pythia 6 by several persons).
1689	</li>
1690
1691	<li>Bug fixes for <code>rootexamples/Makefile</code> and restoration
1692	of some deleted information in <code>rootexamples/README</code>.
1693	Thanks to Axel Naumann and Bernhard Meirose.</li>
1694
1695	<li>Bug fix, so that displaced vertices are possible in resonance
1696	decay chains. Thanks to Daniel Blackburn and Andy Buckley for
1697	pointing this out.</li>
1698
1699	<li>Bug fix for <code>Info</code> counter 2.</li>
1700
1701	<li>Bug fix so that sextet quarks now are read in correctly from
1702	Les Houches Event files; previously the (anti)colours were set
1703	to 0.</li>
1704
1705	<li>Year updated to 2012 in copyright statements etc.</li>
1706
1707	<li>Reformatting to reduce the number of code lines with more
1708	than 79 characters.</li>
1709
1710	<li><code>Pythia::initSLHA()</code> moved from <code>public</code>
1711	to <code>private</code>.
1712	</li>
1713
1714	<li>Remove warning message when tau polarization is set by hand.</li>
1715
1716	<li>Several minor changes to reduce the number of warnings issued
1717	by the clang compiler. The origin of some warnings remains unclear
1718	so those remain to track down (could also be compiler bugs; note that
1719	we discuss warnings, not errors). Thanks to Randy MacLeod for bringing
1720	this up.</li>
1721
1722	<li>The worksheet has been updated to be in step with Pythia 8.160.</li>
1723
1724	<li>Several other minor corrections in the code and documentation.</li>
1725
1726	</ul>
1727	</li>
1728
1729	<li>8.162: 12 March 2012
1730	<ul>
1731
1732	<li>A new option allows for several partons to share the recoil in
1733	final-state radiation, see<?php $filepath = $_GET["filepath"];
1734	echo "<a href='TimelikeShowers.php?filepath=".$filepath."' target='page'>";?>Timelike
1735	Showers</a>. It is mainly intended to be used in the context of
1736	matching to matrix elements, and so only to be used in the first
1737	few branchings.</li>
1738
1739	<li>Several new processes for LED dijet production, see
1740	<?php $filepath = $_GET["filepath"];
1741	echo "<a href='ExtraDimensionalProcesses.php?filepath=".$filepath."' target='page'>";?>Extra Dimensions</a>.</li>
1742
1743	<li>Small update of the <code>Sigma2ffbar2LEDllbar</code> and
1744	<code>Sigma2ffbar2LEDgammagamma</code> LED processes.</li>
1745
1746	<li>New <code>Sigma2QCffbar2llbar</code>
1747	<?php $filepath = $_GET["filepath"];
1748	echo "<a href='CompositenessProcesses.php?filepath=".$filepath."' target='page'>";?>contact interaction</a>
1749	process.</li>
1750
1751	<li>Inclusion of a new method in the
1752	<?php $filepath = $_GET["filepath"];
1753	echo "<a href='MatrixElementMerging.php?filepath=".$filepath."' target='page'>";?>matrix-element merging</a>
1754	framework to influence the construction of histories, e.g. to already
1755	in the construction of histories disallow paths that fail the
1756	<i>2 -> 2</i> cuts.</li>
1757
1758	<li>Further minor updates of the matrix-element merging code,
1759	mainly for improved clarity.</li>
1760
1761	<li>Minor bug fix in the handling of beam and event information fed
1762	in from an <code>LHAup</code> instance.</li>
1763
1764	<li>Minor bug fix for potential crashes from uninitialized variables
1765	for the merging machinery when merging is not used.</li>
1766
1767	<li>Updated History class for matrix element merging,
1768	also avoiding some compiler warnings.</li>
1769
1770	<li>Bug fixes in the handling of correlated mass choices in resonance
1771	decays, such as <i>H -> Z^0 Z^0</i>.</li>
1772
1773	<li>Bug fix when the process-level execution is switched off,
1774	where <code>Info::isResolved()</code> could be called before its
1775	value was initialized. Thanks to Christian Pulvermacher
1776	for finding this.</li>
1777
1778	<li>Corrected matrix-element expression for mass selection in
1779	<i>A^0 -> Z^0 Z^0</i> and <i>A^0 -> W^+ W^-</i>.</li>
1780
1781	<li>SM Higgs mass updated to 125 GeV and default width and branching
1782	ratios modified accordingly. Minor technical improvements of width
1783	calculation.</li>
1784
1785	<li>The usage of nested classes has been removed from
1786	<code>SusyLesHouches</code>, since it could give compilation errors
1787	on some platforms. The new class names begin with <code>LH</code>
1788	and all classes have been put inside the <code>Pythia8</code>
1789	namespace.</li>
1790
1791	<li>Minor Makefile updates. Thanks to Mikhail Kirsanov.</li>
1792
1793	<li>Minor changes to avoid some clang compiler warnings on the
1794	Mac OS X platform.</li>
1795
1796	</ul>
1797	</li>
1798
1799	<li>8.163: 27 March 2012
1800	<ul>
1801
1802	<li>New methods in the
1803	<?php $filepath = $_GET["filepath"];
1804	echo "<a href='EventInformation.php?filepath=".$filepath."' target='page'>";?><code>Info</code></a> class,
1805	<code>id1pdf()</code>, <code>id2pdf()</code>, <code>x1pdf()</code>
1806	and <code>x2pdf()</code>, to denote the partons for which parton
1807	distribution values have been defined. Previously this was assumed
1808	to agree with the incoming partons to the hard process, the same
1809	methods without the <code>pdf</code> qualifier. However, now the
1810	POWHEG approach offers a counterexample. Also the reading and
1811	handling of Les Houches (and other) events, and the interface
1812	to HepMC, has been modified accordingly.
1813	</li>
1814
1815	<li>The decay of Higgs and top resonances read in from Les Houches
1816	Event files is now performed with angular correlations as for
1817	internal processes. LHE files should normally contain all process-specific
1818	resonance decay chains and, if not, decays are made isotropic.
1819	The <i>H -> WW/ZZ -> f fbar f' fbar'</i> and
1820	<i>t -> b W -> b f fbar</i> correlations are process-independent,
1821	however, and thus can be handled internally. If part of the decay
1822	chain has already been set, e.g. <i>H -> WW/Z></i> or <i>t -> b W</i>,
1823	then the subsequent decays are still isotropic.</li>
1824
1825	<li>Updated instructions how to link to HepMC,
1826	in <code>README.HepMC</code>.</li>
1827
1828	<li>Bug fix in the turn-on of resolved diffraction for low
1829	CM energies. Thanks to Erwin Visser.</li>
1830
1831	<li>Bug fix in the handling of string junctions at very high energies,
1832	caused by numerical errors. Thanks to Erwin Visser.</li>
1833
1834	<li>Some other small changes, mainly aesthetics.</li>
1835
1836	</ul>
1837	</li>
1838
1839	<li>8.165: 8 May 2012
1840	<ul>
1841
1842	<li>The MBR (Minimum Bias Rockefeller) model for single, double and
1843	central diffraction [<a href="Bibliography.php" target="page">Cie12</a>] is included as new option
1844	<?php $filepath = $_GET["filepath"];
1845	echo "<a href='Diffraction.php?filepath=".$filepath."' target='page'>";?><code>Diffraction:PomFlux = 5</code></a>.
1846	It is specifically intended for <i>p p</i> and <i>pbar p</i>
1847	interactions, and is currently the only option that also supports
1848	central diffraction. Thus the basic machinery for Central Diffraction
1849	(a.k.a. Double Pomeron Exchange) has now been implemented.
1850	See <code>examples/main04.cc</code> for an example.
1851	Thanks to Robert Ciesielski for contributing the new code.
1852	</li>
1853
1854	<li>For a <i>tau</i> lepton in an external process, by default the
1855	SPINUP number in the Les Houches Accord now is interpreted as giving
1856	the <i>tau</i> helicity, and is used for its decay.</li>
1857
1858	<li>A <i>tau</i> coming from a <i>W</i> now defaults to being purely
1859	lefthanded when neither of the existing matrix elements apply.</li>
1860
1861	<li>Decay mode <i>t -> H+ b</i> included as an option.</li>
1862
1863	<li>Four ATLAS tunes have been implemented as options for
1864	<code>Tune:pp</code>: A2-minbias-mstw2008lo, AU2-cteq6l1, AU2-mstw2008lo,
1865	and AU2-ct10. The new flag <code>Tune:preferLHAPDF</code> can be used
1866	to switch between the LHAPDF and the internal implementation of a
1867	PDF set, in cases where both are available.</li>
1868
1869	<li>Reorder libraries in <code>examples/Makefile</code>, specifically
1870	move <code>LIBGZIP</code> so that it is properly linked when used.
1871	Thanks to Erik Schnetter.</li>
1872
1873	<li>Minor modification so that LHAPDF can be used for PDFs in the hard
1874	process, with one of the built-in PDFs for the rest, even if LHAPDF is
1875	compiled so as to handle only one concurrent PDF set.</Li>
1876
1877	<li>Bug fix, that <code>ParticleDecays:mixB = off</code> did not
1878	switch off <i>B0 - B0bar</i> and <i>Bs0 - Bs0bar</i> mixing.
1879	Thanks to James Catmore.</li>
1880
1881	<li>Bug fix for the handling of gluon polarization of initial-state
1882	radiation, where an anisotropic azimuthal distribution was inadvertently
1883	generated in some <i>2 -> 1</i> processes. The update also includes
1884	always setting the second daughter zero for the two partons coming in to
1885	a hard <i>2 -> 1</i> process. Thanks to Antonio Policicchio.</li>
1886
1887	<li>Bug fix, that the setting of the number of user hooks MPI steps did
1888	not use <code>UserHooks::canVetoMPIStep()</code> properly.</li>
1889
1890	<li>Some other small changes, mainly documentation and aesthetics.</li>
1891
1892	</ul>
1893	</li>
1894
1895	<li>8.170: 21 September 2012
1896	<ul>
1897
1898	<li>Streamline default behaviour and options for choice of GeV or MeV
1899	for output to the HepMC event format, see
1900	<?php $filepath = $_GET["filepath"];
1901	echo "<a href='HepMCInterface.php?filepath=".$filepath."' target='page'>";?>HepMC Interface</a>.
1902	Also set the mass of HepMC particles explicitly, rather than having
1903	it calculated implicitly. Thanks to James Monk and Andy Buckley.</li>
1904
1905	<li>The <i>tau</i> decay machinery has been further augmented with
1906	matrix elements and form factors for a variety of decay modes, such
1907	that all modes with a branching ratio above 0.1% are fully modelled.
1908	Several new classes and methods have been added to this end,
1909	Also, a <i>tau</i> pair coming from a <i>Z^0</i> decay is now
1910	handled by assuming the <i>Z^0</i> to be unpolarized when neither
1911	of the existing matrix elements apply. Taus coming from B baryons are
1912	handed as for B mesons.</li>
1913
1914	<li>Flavour violating decays have been added to the squark, gluino,
1915	neutralino and chargino decay tables.</li>
1916
1917	<li>Extend the <code>UserHooks::subEvent(...)</code> method so that it
1918	also works passably at the process level. Also new option for
1919	<code>UserHooks::omitResonanceDecays(...)</code>.</li>
1920
1921	<li>New methods <code>UserHooks::canVetoPartonLevelEarly()</code>
1922	and <code>UserHooks::doVetoPartonLevelEarly( const Event&)</code>
1923	are intended to be used the same way as the existing ones without
1924	<code>Early</code> in their names, but allow veto right after
1925	the ISR + FSR + MPI evolution, before beam remnants are added and
1926	resonance decays are considered.</li>
1927
1928	<li>Central diffraction now available for all
1929	<code><?php $filepath = $_GET["filepath"];
1930	echo "<a href='Diffraction.php?filepath=".$filepath."' target='page'>";?>PomFlux</a></code>
1931	options, not only the MBR model. This has been constructed by analogy
1932	with the respective assumptions made for single diffraction, but
1933	includes some arbitrariness. Therefore the cross section is left
1934	easily rescaleable and, for backwards compatibility with tunes
1935	that does not contain it, easily possible to switch off, see
1936	the <?php $filepath = $_GET["filepath"];
1937	echo "<a href='TotalCrossSections.php?filepath=".$filepath."' target='page'>";?>relevant section</a>.
1938	</li>
1939
1940	<li>Reading of ALPGEN parameter and event files has been added,
1941	see <?php $filepath = $_GET["filepath"];
1942	echo "<a href='AlpgenAndMLM.php?filepath=".$filepath."' target='page'>";?>ALPGEN and MLM Merging</a>.
1943	</li>
1944
1945	<li>MLM matching has been added, as a first step for ALPGEN events,
1946	see <?php $filepath = $_GET["filepath"];
1947	echo "<a href='AlpgenAndMLM.php?filepath=".$filepath."' target='page'>";?>ALPGEN and MLM Merging</a>.
1948	</li>
1949
1950	<li>The CKKW-L merging machinery has been upgraded in a number of respects.
1951	<br/>- More thorough treatment of <code>pp>bb~e+e-veve~</code> with
1952	additional <i>b</i>-jets.
1953	<br/>- Corrected hard <i>mu_r</i> and <i>mu_f</i> choices for
1954	dijet and promt photon.
1955	<br/>- More ways to define a hard process, e.g. with the LEPTONS and
1956	NEUTRINO tags. The merging will understand LHE files for mixed processes
1957	(e.g. <i>W+</i> and <i>W-</i> production together).
1958	<br/>- More merging scale definitions.
1959	<br/>- More freedom to generate all possible histories.
1960	<br/>- Internal check (and cut) on Les Houches events in
1961	<code>Pythia::mergeProcess</code> if merging scale value of the events
1962	is below the value given to Pythia by setting <code>Merging::TMS</code>.
1963	</li>
1964
1965	<li>It now works to have R-parity violating decays of R-hadrons,
1966	i.e. baryon number violation in a vertex displaced from the primary
1967	one.</li>
1968
1969	<li>The documentation of diffractive processes by the
1970	<code><?php $filepath = $_GET["filepath"];
1971	echo "<a href='EventInformation.php?filepath=".$filepath."' target='page'>";?>Info</a></code>
1972	methods has been expanded and corrected. This also include the
1973	<code>list()</code> method.</li>
1974
1975	<li>Particle masses and widths have been updated to agree with the
1976	2012 RPP values [<a href="Bibliography.php" target="page">Ber12</a>]. Thanks to Piotr Zyla for data file
1977	and James Catmore for program to update the PYTHIA tables from this
1978	input.</li>
1979
1980	<li>New methods <code>jetAssignment</code> and <code>removeJet</code>
1981	added to the <code>SlowJet</code> class.</li>
1982
1983	<li>Introduce angular correlation in decay chain
1984	<i>H -> gamma Z0 -> gamma f fbar</i>. Thanks to Tim Barklow and
1985	Michael Peskin.</li>
1986
1987	<li>Introduce simple way to bias the selection of <i>2 -> 2</i>
1988	processes towards larger <i>pT</i> values, with a compensatingly
1989	decreasing event weight, see
1990	<?php $filepath = $_GET["filepath"];
1991	echo "<a href='PhaseSpaceCuts.php?filepath=".$filepath."' target='page'>";?>Phase Space Cuts</a>. Only offers a
1992	subset of the possibilities allowed by <code>UserHooks</code>,
1993	but simpler to use. The <code>main08.cc</code> program has been
1994	expanded to illustrate this possibility, and also expanded to
1995	include low-<i>pT</i> subsamples.</li>
1996
1997	<li>The two remaining non-NLO tunes from [<a href="Bibliography.php" target="page">ATL12</a>] are now
1998	included.</li>
1999
2000	<li>The <code><?php $filepath = $_GET["filepath"];
2001	echo "<a href='EventInformation.php?filepath=".$filepath."' target='page'>";?>Info</a></code> methods
2002	<code>nTried, nSelected, nAccepted, sigmaGen</code> and
2003	<code>SigmaErr</code> now takes the code of an individual process
2004	as an optional argument.</li>
2005
2006	<li>It is now possible to generate resonance decays, followed by
2007	showers and hadronization, without having them associated with any
2008	specific process. This is part of an expanded
2009	<?php $filepath = $_GET["filepath"];
2010	echo "<a href='HadronLevelStandalone.php?filepath=".$filepath."' target='page'>";?>Hadron-Level Standalone</a>
2011	machinery, as before triggered by <code>ProcessLevel = off</code>,
2012	but additionally requiring <code>Standalone:allowResDec = on</code>.
2013	Input can either be directly into the <code>event</code>
2014	event record or via a (simplified) Les Houches Event File.</li>
2015
2016	<li>New <code>configure</code> script options <code>--installdir</code>,
2017	<code>--prefix</code> and <code>--datadir</code> can be used to set the
2018	location(s) to which the library, header and data directories
2019	will be copied by a <code>make install</code> subsequent to the
2020	<code>make</code>. Thanks to Mikhail Kirsanov.</li>
2021
2022	<li>Fix charge in antiparticle name when particle read in from SLHA
2023	file. Thanks to Johan Alwall.</li>
2024
2025	<li>Pointers now only compared with == and != (not e.g. > 0), to avoid
2026	warnings in gcc 4.7.</li>
2027
2028	<li>New check that version number of the code matches that of the
2029	XML files. If not, no events can be generated. Thanks to James Monk
2030	for suggestion.</li>
2031
2032	<li>New check that mother and daughter indices have been set to give
2033	a consistent event history. Can be switched on/off with the new
2034	<code>Check:history</code> flag.</li>
2035
2036	<li>A new method <code>LHAup::newEventFile</code> has been added to
2037	switch to reading in events from another LHE file without having to
2038	reinitialize the whole class. Lower-level routines like
2039	<code>openFile</code> and <code>closeFile</code> have been added to
2040	handle correct order of operations also when an intermediate gzip
2041	decompression step is involved.</li>
2042
2043	<li><code>LHAup::eventLHEF()</code> can now be called with an optional
2044	argument <code>false</code>, to make event files somewhat smaller by
2045	reducing the amount of blanks.</li>
2046
2047	<li>A new mode <code>Beams:nSkipLHEFatInit</code> introduced to
2048	skip ahead the first few events in a Les Houches Event File (cf. the
2049	<code>LHAup::skipEvent(nSkip)</code> method).</li>
2050
2051	<li>Introduce a new pair of user hooks that can be used to reject
2052	the sequence of hard-process resonance decays, without rejecting
2053	the production of the primary resonances.</li>
2054
2055	<li>The possibility of separate multiplicative prefactors to the
2056	renormalization and factorization default <i>pT^2</i> scale has been
2057	introduced for both timelike and spacelike showers.</li>
2058
2059	<li>Bug fixes in history information for R-hadron production, which also
2060	fixes HepMC conversion in this case.</li>
2061
2062	<li>Bug corrected in <code>SigmaSusy.cc</code>, for chargino+neutralino
2063	production. Indexing error for incoming quark states in the process
2064	<code>Sigma2qqbar2charchi0</code>, resulted in incorrect CKM factors.</li>
2065
2066	<li>Corrected a bug in <code>SusyLesHouches.cc</code>, for NMSSM spectra.
2067	The unitarity check on the neutralino mixing matrix was faulty, leading
2068	to erroneous messages about unitarity violations and SUSY being switched
2069	off.</li>
2070
2071	<li>Bug fixes in the handling of resolved and unresolved diffractive events.
2072	Thanks to Robert Ciesielski for debug.</li>
2073
2074	<li>Do not set up FSR dipoles for <i>2 -> 1</i> processes.</li>
2075
2076	<li>Check that some channel open for resonance decays. Also further
2077	check whether resonance decay treatment should be invoked.</li>
2078
2079	<li>Bug fix in reading of particle names from SLHA input.</li>
2080
2081	<li>Change mass, width and decay mode(s) of D*_s(10431). Thanks to
2082	Michal Petran.</li>
2083
2084	<li>Bug fix in leptoquark production (lepton sign in
2085	<i>q g -> LQ l</i>).</li>
2086
2087	<li>New argument added to <code>SpaceShower::reassignBeamPtrs</code>
2088	for diffractive event processing, as already available for
2089	<code>TimeShower</code>.</li>
2090
2091	<li>Do not write warnings in <code>SpaceShower</code> for weights
2092	above unity if the evolution scale is below 1 GeV^2.</li>
2093
2094	<li>Add default values for member variables in some constructors,
2095	and some related changes for <code>AlphaStrong</code> code.</li>
2096
2097	<li>Warn if negative-energy parton in hadronization.</li>
2098
2099	<li>The MPI <i>pT</i> values assumed in the beam remnant setting
2100	of primordial <i>kT</i> and colour reconnection probability were
2101	incorrect for diffractive events.</li>
2102
2103	<li>The arrays with MPI information were not reset when parton or
2104	hadron level fails and a new try is made. Only affected few events.</li>
2105
2106	<li>MPI statistics can not yet be accumulated for diffractive events,
2107	and therefore the relevant routine is no longer called.</li>
2108
2109	<li>Bug fix in the double parton scattering suppression from
2110	energy-momentum conservation.</li>
2111
2112	<li>Outgoing proton masses were not set in the event record for
2113	elastic scattering (but kinematics handling was correct).</li>
2114
2115	<li>Bug fixes in the identification and documentation of junctions,
2116	previously leading to some unnecessarily rejected events. Also
2117	other improvements leading to fewer errors.</li>
2118
2119	<li>Slightly increased values for FragmentationSystems:mJoin and
2120	StringFragmentation::FACSTOPMASS to reduce failure rate, without
2121	noticeably affecting event properties.</li>
2122
2123	<li>The Les Houches cross section error is now taken into account
2124	in the final Pythia error for strategies +-3. New methods
2125	<code>LHAup::xSecSum()</code> and <code>LHAup::xErrSum()</code>
2126	provide the necessary information.
2127	</li>
2128
2129	<li>When a tau pair comes from a massless photon, in dipole shower
2130	evolution, for the decay description the mother photon is reassigned
2131	to have the sum of the tau momenta.</li>
2132
2133	<li>Minor change in initialization sequence for user hooks,
2134	to allow for more flexibility.</li>
2135
2136	<li>Do not print warnings when multiparton interaction weights are
2137	only slightly above unity.</li>
2138
2139	<li>Do not write warnings for three known particles that are so close
2140	to threshold that widths are switched off to avoid trouble.</li>
2141
2142	<li>Some minor typographical changes.</li>
2143
2144	</ul>
2145	</li>
2146	</ul>
2147
2148	</body>
2149	</html>
2150
2151	<!-- Copyright (C) 2012 Torbjorn Sjostrand -->

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