Context Navigation

← Previous Revision
Latest Revision
Next Revision →
Blame
Revision Log

UpdateHistory.html @ 1

Last change on this file since 1 was 1, checked in by zerwas, 11 years ago
first import of structure, PYTHIA8 and DELPHES
File size: 91.6 KB

Line
1	<html>
2	<head>
3	<title>Update History</title>
4	<link rel="stylesheet" type="text/css" href="pythia.css"/>
5	<link rel="shortcut icon" href="pythia32.gif"/>
6	</head>
7	<body>
8
9	<h2>Update History</h2>
10
11	These update notes describe major updates relative to the baseline
12	PYTHIA 8.100 version. However, they are less extensive than the
13	corresponding update notes for PYTHIA 6. On the other hand,
14	whereas the PYTHIA 6 manual is a static document, the PYTHIA 8
15	html/php pages are kept up to date for each subversion.
16
17	<br/><br/>
18	<b>Important note:</b>version 8.160 does introduce some elements of
19	backwards incompatibility. Specifically, "multiple interactions",
20	abbreviated MI, haa been renamed "multiparton interactions", MPI.
21	This affects many parts of the code and documentation. Also some
22	features are deprecated, although remaining until the end of the
23	8.1xx version series.
24
25
26	<h3>Main news by version</h3>
27
28	<ul>
29
30	<li>8.105: 24 February 2008
31	<ul>
32
33	<li>New option to initialize with arbitrary beam directions<br/>
34	<code>pythia.init( idA, idB, pxA, pyA, pzA, pxB, pyB, pzB)</code></li>
35
36	<li>Added capability to set <a href="BeamParameters.html" target="page">beam energy spread
37	and beam vertex</a>.
38	<br/>
39	<b>Warning:</b> as a consequence, the old <code>Beams</code> group of
40	settings has been moved to <code>BeamRemnants</code>, and
41	<code>Beams</code> is now instead used for machine beam parameters.
42	Therefore also some <code>Main</code> settings of this character have been
43	regrouped, as follows:
44	<table cellspacing="5">
45	<tr> <td>8.100 setting </td> <td>has been moved to </td> </tr>
46	<tr> <td><code>Main:idA </code></td>
47	<td><code>Beams:idA </code></td> </tr>
48	<tr> <td><code>Main:idB </code></td>
49	<td><code>Beams:idB </code></td> </tr>
50	<tr> <td><code>Main:inCMframe </code></td>
51	<td>(<code>Beams:frameType</code>) </td> </tr>
52	<tr> <td><code>Main:eCM </code></td>
53	<td><code>Beams:eCM </code></td> </tr>
54	<tr> <td><code>Main:eA </code></td>
55	<td><code>Beams:eA </code></td> </tr>
56	<tr> <td><code>Main:eB </code></td>
57	<td><code>Beams:eB </code></td> </tr>
58	<tr> <td><code>Main:LHEF </code></td>
59	<td><code>Beams:LHEF </code></td> </tr>
60	</table></li>
61
62	<li>The <code>forceHadronLevel()</code> method introduced for standalone
63	hadronization.</li>
64
65	<li><code>main15.cc</code> illustrated how either full hadronization or
66	only decays of some particles can be looped over for the rest of the
67	event retained.</li>
68
69	<li>The <code>LHAevnt</code> and <code>LHAinit</code> classes have been
70	joined into a new <code>LHAup</code> one, with new options that allow
71	the writing of a Les Houches Event File.</li>
72
73	<li>The <code>SusyLesHouches</code> class updated to handle
74	SLHA version 2.</li>
75
76	<li>Updated HepMC conversion routine.</li>
77
78	<li>The static <code>ErrorMsg</code> class has been removed and
79	its functionality moved into the non-static <code>Info</code> class,
80	in the renamed Info file.</li>
81
82	<li>Further reduction of the use of static, with related code changes.
83	This should allow to have several almost independent <code>Pythia</code>
84	instances. Some static classes still remain, however, notably for
85	random number generation and particle properties.</li>
86
87	<li>Limited capability to use two different <code>Pythia</code> instances
88	for signal + pileup event generation, see <code>main19.cc</code> for an
89	example.</li>
90
91	<li>In the <code>Event</code> class the <code>=</code> and
92	<code>=+</code> methods have been overloaded to allow the copying
93	or appending of event records. Illustrated in <code>main19.cc</code>.</li>
94
95	<li>The html and php page formatting improved with
96	cascading style sheets.</li>
97
98	<li>Several minor improvements and new options, including updated configure
99	scripts.</li>
100
101	</ul>
102	</li>
103
104	<li>8.108: 1 May 2008
105	<ul>
106
107	<li>Correction in the event record, so that the beam particles in line
108	1 and 2 do not have any mother according to the <code>motherList</code>
109	method. Previously the "system" entry in line 0 was counted as their
110	mother, which gave rise to an unexpected extra vertex in the conversion
111	to the HepMC format.</li>
112
113	<li>Support for HepMC version 1 is removed, to simplify the code and
114	reflect the evolution of the field.</li>
115
116	<li>Status codes are stored in HepMC only as 1 for existing and 2 for
117	decayed or fragmented particles (whereas previously the original PYTHIA
118	codes were used for the latter).</li>
119
120	<li>Parton densities are stored in HepMC as <i>xf(x,Q^2)</i>
121	rather than the <i>f(x,Q^2)</i> used in (some) previous versions.</li>
122
123	<li>The SusyLesHouches class has ben updated so that reading is fully
124	compatible with the SLHA2 standard. </li>
125
126	<li>Improved handling of the Higgs width, relevant for massive and thereby
127	broad resonance shapes.</li>
128
129	<li>The matrix elements for neutralino pair production have now been
130	completed and checked.</li>
131
132	<li>Ensure that <i>alpha_strong</i> does not blow up, by introducing
133	a minimal scale somewhat above <i>Lambda_3</i> (roughly where
134	<i>alpha_strong = 10</i>).</li>
135
136	<li>New methods <code>isValence1()</code> and <code>isValence2()</code>
137	in the <code>Info</code> class.</li>
138
139	<li>Protection against division by zero in calculation of decay vertex
140	(for zero-mass gluons with zero lifetime, where there should be no
141	displacement).</li>
142
143	<li>A new compilation option <code>-Wshadow</code> is introduced and
144	code is rewritten at all places where this option gave warnings.</li>
145
146	<li>Minor library correction to allow compilation with gcc 4.3.0.</li>
147
148	</ul>
149	</li>
150
151	<li>8.114: 22 October 2008
152	<ul>
153
154	<li>New rescattering description operational (but still experimental)
155	for the case that FSR is not interleaved, but saved until after MPI,
156	ISR and beam remnants have been handled. This involves much new code
157	in several classes.</li>
158
159	<li>A new class <code>PartonSystems</code> is introduced to
160	keep track of which partons in the event record belong to which
161	subcollision system, plus some further information on each subsystem.
162	It takes over functionality previously found as part of the
163	<code>Event</code> class, but leaves room for future growth.</li>
164
165	<li>Add optional model, wherein an increased <i>pT0</i> turnoff scale
166	for MPI and ISR is used for above-average active events, i.e. events that
167	already have several MPI's or ISR emissions.</li>
168
169	<li>Freeze GRV 94L distribution at small <i>Q^2</i> to avoid blowup.</li>
170
171	<li>The <code>pythia.readFile(...)</code> method can now alternatively take
172	an <code>istream</code> as argument instead of a <code>filename</code>.</li>
173
174	<li>Minor bug correction in <code>PartonLevel.cc</code>; the bug could
175	(rarely) give a segmentation fault.</li>
176
177	</ul>
178	</li>
179
180	<li>8.120: 10 March 2009
181	<ul>
182
183	<li>New rescattering description further developed, but not yet
184	recommended for normal usage.</li>
185
186	<li>Include new processes for Large Extra Dimensions and Unparticles,
187	contributed by Stefan Ask. New test program <code>main28.cc</code>
188	illustrates.</li>
189
190	<li>Include further SUSY processes: neutralino-chargino and
191	chargino-chargino pairs. The processes should be valid also
192	in the case of non-minimal flavour violation and/or CP violation.
193	Expanded machinery to keep track of SUSY parameters.</li>
194
195	<li>Include backwards evolution of incoming photon as part of the
196	<code>SpaceShower</code> initial-state radiation description. This
197	allows you to simulate hard collisions where one of the incoming
198	partons is a photon. New test program <code>main43.cc</code>
199	illustrates.</li>
200
201	<li>Allow separate mass and transverse momentum cuts when two hard
202	subprocesses are generated in the same event.</li>
203
204	<li>The default value for the border between short- and long-lived
205	paticles has been changed from 1 mm to 10 mm, to better conform with
206	LHC standards, see <a href="ParticleDecays.html" target="page">here</a>.
207	The default is still to let all unstable particles decay.</li>
208
209	<li>New ISR matrix-element correction to <i>f -> f gamma</i>
210	in single <i>W</i> production.</li>
211
212	<li>New method <code>Event::statusHepMC</code> returns the status
213	code according to the HepMC conventions agreed in February 2009.
214	The interface to HepMC now writes out status according to this
215	convention.</li>
216
217	<li>Add capability to link to FastJet, with expanded configure script
218	and Makefile, and with <code>main61.cc</code> as new example.</li>
219
220	<li>Update of <code>Makefile.msc</code>, with added support for latest
221	Visual C++ Express edition and use of regexp to check nmake version.</li>
222
223	<li>Update of <code>LHAFortran.h</code> and
224	<code>Pythia6Interface.h</code>, to make the interface to Fortran
225	routines work also under Windows. (Thanks to Anton Karneyeu.)
226
227	<li>Updated and expanded worksheet.</li>
228
229	<li>The manual pages in the <code>xmldoc</code> directory, and thereby
230	also those of the <code>htmldoc</code> and <code>phpdoc</code>
231	directories, have been significantly updated and expanded. In particular,
232	in many places the class of each method is explicitly shown, as well as
233	the type of the return value and of the arguments. This upgrade is not
234	yet completed, but already covers the more relevant sections. </li>
235
236	<li>The unary minus operator in the <code>Vec4()</code> returns a
237	reference to a four-vector with all components negated, but leaves
238	the original four-vector unchanged. Previously the four-vector itself
239	was flipped.</li>
240
241	<li>The <code>pPlus()</code> and <code>pMinus()</code> methods of a
242	four-vector and an event-record particle are renamed <code>pPos()</code>
243	and <code>pNeg()</code>, respectively.</li>
244
245	<li>Include a further loop in <code>ProcessLevel</code>, so that a new
246	process is generated in case of failures of a less severe nature.</li>
247
248	<li>Introduce warning message for unexpected <code>meMode</code> in
249	<code>ResonanceWidths</code>.</li>
250
251	<li>Les Houches event reading framework has been rearranged for
252	more flexibility. Some bugs corrected. Specifically, when scale
253	is not set (<code>scale = -1.</code> in the Les Houches standard),
254	PYTHIA did not attempt to set this scale itself, which typically
255	lead to there not being any ISR or FSR. Now the
256	<a href="CouplingsAndScales.html" target="page">rules for normal
257	1-, 2- and 3-body final states</a> are applied, with a trivial
258	extension of the 3-body rules for higher multiplicities.</li>
259
260	<li>Correct bug in the handling of parton densities, whereby it was
261	not possible to switch to a new set, once a first initialization
262	had been done.</li>
263
264	<li>Correct bugs when several <code>Pythia::init</code> initialization
265	calls are made in the same run, specifically in the case that pointers
266	to external processes have been handed in.
267
268	<li>Changes in <code>main03.cmnd</code> and <code>main04.cmnd</code>
269	so that some nonstandard options are commented ou rather than active.
270	Related comments inserted also in some other <code>.cmnd</code> files,
271	but there without any change in program execution.</li>
272
273	<li>A few further minor bug fixes.</li>
274
275	<li>Update year to 2009.</li>
276
277	</ul>
278	</li>
279
280	<li>8.125: 16 June 2009
281	<ul>
282
283	<li>Hadronization and timlike-shower parameter default values updated
284	according to a tune to LEP1 data by Hendrik Hoeth, using the
285	Rivet + Professor framework.</li>
286
287	<li>Many further SUSY production processes. SLHA readin expanded to cover
288	also masses and decay modes. Example <code>main22.cc</code> updated, while
289	<code>main33.cc</code> now superfluous and removed. </li>
290
291	<li>Also further processes for extra dimensions.</li>
292
293	<li>Stefan Ask joins as coauthor.</li>
294
295	<li>The <code>TimeShower::shower(...)</code> method has gained
296	a new argument, that forces the shower evolution to stop after
297	a given number of branchings. A new method
298	<code>TimeShower::pTLastInShower()</code> permits the last evolution
299	<i>pT</i> to be read out. These extensions can be useful
300	for matching studies.
301	</li>
302
303	<li>New optional argument <code>isInterleaved</code> added to
304	<code>TimeShower::branch(...)</code>. Is false by default, but
305	true when called from the parton level for interleaved evolution
306	of several parton systems, optionally also with ISR and MPI.</li>
307
308	<li>New methods <code>UserHooks::canSetResonanceScale()</code>
309	and <code>UserHooks:scaleResonance(...)</code> allows an optional
310	user choice of the maximum shower scale in resonance decays.</li>
311
312	<li>A new method <code>SpaceShower::doRestart()</code> has been
313	added, to help distinguish cases when a
314	<code>SpaceShower::branch(...)</code> failure forces a complete
315	restart of the evolution from ones where only the intended
316	current branching has been vetoed.
317
318	<li>When multiparton interactions are initialized, it is now
319	possible to reduce both <i>pT0</i> and <i>pTmin</i>
320	if necessary to find a valid solution where
321	<i>sigma_jet > sigma_nondiffractive</i>. Previously
322	only the former would be reduced, which could lead to
323	infinite loops if too large a <i>pTmin</i> was used.
324	Thanks to Sami Kama for pointing out the problem.
325	</li>
326
327	<li>The rescattering machinery is now essentially completed, and can
328	be used also by others than the authors. For now, however, it can only
329	be recommended for dedicated studies, not e.g. for generic tunes.
330	</li>
331
332	<li>Timelike and spacelike showers, and beam remnant handling,
333	are modified to handle rescattering partons. Specifically, a new machinery
334	is introduced to trace the recoils from the combination of rescattering
335	with showers and primordial <i>kT</i>. Can assign space- or timelike
336	virtualities to intermediate particles to have energy and momentum
337	conserved locally. This affects the <code>PartonLevel</code>,
338	<code>MultipartonInteractions</code>, <code>TimeShower</code>,
339	<code>SpaceShowe</code>r and <code>BeamRemnants</code> classes.
340	Further details to appear in the upcoming article on rescattering.
341	(Another change is a reversal to pre-8.114 order for non-interleaved FSR,
342	wherein also FSR is treated before beam remnants are attached.)
343	</li>
344
345	<li>Four new status codes introduced, as part of the rescattering
346	description:
347	<br/>45 : incoming rescattered parton, with changed kinematics owing
348	to ISR in the mother system (cf. status 34);
349	<br/>46 : incoming copy of recoiler when this is a rescattered parton
350	(cf. status 42);
351	<br/>54 : copy of a recoiler, when in the initial state of a different
352	system from the radiator;
353	<br/>55 : copy of a recoiler, when in the final state of a different
354	system from the radiator.
355	</li>
356
357	<li>New method <code>Info::tooLowPTmin()</code> can tell whether the
358	<i>pTmin</i> scales for showers or multiparton interactions are too low.
359	</li>
360
361	<li>Pion beams allowed, both <i>pi^+</i>, <i>pi^-</i> and
362	<i>pi^0</i>. New machinery for the latter, where the valence
363	flavour content is chosen to be either <i>d dbar</i> or
364	<i>u ubar</i> for each new event. One internal pion PDF
365	implemented, with others from LHAPDF.</li>
366
367	<li>Treatment of Pomeron-proton collisions begun.</li>
368
369	<li>Phase-space handling of hard processes and multiparton interactions
370	slightly expanded to better allow for harder PDF's than proton ones,
371	e.g. for Pomerons.</li>
372
373	<li>The program documentation has been expanded with an
374	alphabetical index of all methods that are described on the
375	webpages, see the <a href="ProgramMethods.html" target="page">Program Methods</a>
376	page. Also other sections of the documentation have been
377	updated and expanded, including the worksheet.</li>
378
379	<li>Several <code>list</code> methods have been made
380	<code>const</code>. For the listing of events two new methods
381	have been added, <code>Event::list()</code> and
382	<code>Event::list(bool showScaleAndVertex,
383	bool showMothersAndDaughters = false)</code>,
384	that correspond to special cases of the general method.</li>
385
386	<li>A new method <code>Pythia::LHAeventSkip(int nSkip)</code>
387	permits a skip-ahead of the reading of external Les Houches
388	Events, without the necessity to generate the intervening
389	<code>nSkip</code> events in full. Makes use of the new
390	<code>LHAup::skipEvent(int nSkip)</code> method to perform
391	the operations. Mainly intended for debug purposes.
392
393	<li>The <code>ClusterJet</code> jet finder now saves the last
394	five clustering scales. Also a minor bug fix. Thanks to Nils
395	Lavesson for this contribution.</li>
396
397	<li>The <code>Particle::m2()</code> method now returns a negative
398	number when the stored mass <i>m</i> is negative, as used to
399	indicate spacelike virtualities. Also the
400	<code>Particle::eCalc()</code>, <code>Particle::mT()</code> and
401	<code>Particle::mT2()</code> methods have been modified.
402	</li>
403
404	<li>The <code><<</code> method to print our a four-vector has
405	been expanded with a fifth number, the invariant length, with a minus
406	sign for spacelike vectors, and provided within brackets to allow
407	a simple visual distinction.</li>
408
409	<li>New methods <code>Rndm::dumpState(string fileName)</code> and
410	<code>Rndm::readState(string fileName)</code> allows to write or
411	read the state of the random number generator to or from a binary file.
412	</li>
413
414	<li>New method <code>double GammaReal(double x)</code> returns the
415	value of the <i>Gamma</i> function for arbitrary real argument.
416	Some cross sections for extra-dimensional processes rewritten to
417	make use of it.
418	</li>
419
420	<li>New example program <code>main29.cc</code> shows how
421	to set up a fictitious process of a heavy system decaying
422	to two particles or partons, with decays traced to stable
423	particles, as relevant for astroparticle applications.</li>
424
425	<li>Main programs that illustrate the HepMC interface have
426	been updated to use version 2.04, including units and excluding
427	deprecated output formats.</li>
428
429	<li>The <code>main32.cc</code> example extended also to handle
430	Les Houches Event Files.</li>
431
432	<li>The Makefile has been modified so that "make clean" only
433	removes the current compilation and library fles, while
434	"make distclean" gives a more extensive reset and cleanup.
435	Thanks to Nils Lavesson for this contribution. Some other
436	minor Makefile corrections.</li>
437
438	<li>Several main programs that use the
439	<code>Main:timesToShow</code> mode have been corrected so as
440	not to crash if this is set to zero. Also some other cosmetics
441	changes in main programs that do not affect the running.</li>
442
443	<li>Bug correction, in that previously a veto with user hooks
444	was not propagated from parton showers inside resonance decays.
445	</li>
446
447	<li>Minor bug fix in <code>TimeShower</code> for kinematics with
448	unequal beam-particle masses.</li>
449
450	<li>Bug fix so that <code>PartonLevel:MPI = off</code> also works for
451	minimum-bias events.</li>
452
453	<li>Minor bug fix in the impact-parameter selection of multiparton
454	interactions. Thanks to Sami Kama for pointing it out.</li>
455
456	<li>String fragmentation for junction topology protected against
457	numerical instability in boost.</li>
458
459	<li>Bug correction in the handling of particle decays to partons,
460	where the scale of the partons was set before the partons had been
461	added to some arrays, leading to indexation out of bounds.
462	Thanks to Vladislav Burylov for discovering this bug.
463	</li>
464
465	<li>Bug correction in the handling of particles with inhibited decay,
466	where the decay vertex would be too far displaced, which could lead to
467	infinite loop. Thanks to Sami Kama for debugging this. </li>
468
469	<li>Check to avoid infinite loop in matrix-element handling of
470	two-body decays.</li>
471
472	<li>Bug correction to avoid infinite loops in Dalitz decay treatment.
473	Some changes in the decay handling logic to allow a new try when the
474	decay of a particle fails.</li>
475
476	<li>Minor correction, so the pointer to the <code>Info</code> class
477	is set also for user-written classes derived from <code>LHAup</code>.
478	</li>
479
480	<li>Correction for typo in the matrix element of the
481	<code>Sigma3ff2HchgchgfftWW</code> class, for doubly charged Higgs
482	production. Thanks to Merlin Kole for spotting it.</li>
483
484	<li>Updated colour bookkeeping in junction-antijunction annihilation
485	avoids later problems in <code>Pythia::check()</code>. </li>
486
487	<li>Minor updates of the <code>Makefile.msc</code> file to work with
488	Visual Studio 2008. Thanks to David Bailey for these modifications.</li>
489
490	<li>Ensure that <code>nInit</code> in the <code>BeamParticle</code>
491	class is set also for unresolved lepton beams.</li>
492
493	<li>The <code>VetoEvolution</code> class, derived from
494	<code>UserHooks</code>, is obsolete and has been removed.</li>
495
496	</ul>
497	</li>
498
499	<li>8.130: 15 September 2009
500	<ul>
501
502	<li>New machinery that allows multiparton interactions inside diffractive
503	systems. Also new optional Pomeron flux factors and Pomeron PDFs.
504	New page on <a href="Diffraction.html" target="page">diffraction</a> added, where
505	further details are collected. Still not tuned, so to be used with
506	caution.</li>
507
508	<li>Make Peter Skands' "Tune 1" parameters for ISR and MPI default.
509	The older simpler tune is still available as an option, see
510	<code><a href="Tunes.html" target="page">Tune:pp</a></code>.
511	</li>
512
513	<li>New possible choices for a second hard process: charmonium,
514	bottomonium, top pair and single top.</li>
515
516	<li>New code for pair production of generic colour-triplet scalar,
517	fermion or vector. Largely written by Johan Bijnens, partly recycling
518	existing code.</li>
519
520	<li>Add user hooks possibility to veto event after a given number
521	of multiparton interactions.</li>
522
523	<li>Add instructions how PYTHIA 8 can be used from inside ROOT.
524	Thanks to Andreas Morsch for providing the text and Rene Brun
525	for a simple example.</li>
526
527	<li>The <code>main21.cc</code> example extended with an option
528	for a single-particle gun.</li>
529
530	<li>Improvements and bug fixes in rescattering framework.</li>
531
532	<li>New method <code>Hist::table(string fileName)</code> provides a
533	more direct way to print a two-column table of histogram contents
534	into a file than the current <code>Hist::table(ostream& os = cout)</code>.
535	</li>
536
537	<li>Modify reading of external files so that a line only consisting of
538	control characters counts as empty, the same way as a line only consisting
539	of blanks already did. This includes carriage return, tabs and a few more,
540	the ones represented by <code>\n \t \v \b \r \f \a</code>. Applies to
541	Les Houches Event files, settings files and particle data files. </li>
542
543	<li>Fix it so that the read-in of a Les Houches Event File for the
544	hardest process can be combined with the faciliy to select a specified
545	second hard process.</li>
546
547	<li>New empty base class method <code>LHAup::fileFound()</code>
548	allows the derived class <code>LHAupLHEF</code> to signal more
549	clearly that a failed initialization is caused by a failure to open
550	the desired file. </li>
551
552	<li>Check that a pointer to an <code>LHAup</code> object has been set
553	in <code>Pythia::LHAeventList()</code> and
554	<code>Pythia::LHAeventSkip(...)</code> calls.</li>
555
556	<li>Updated configure and Makefile, e.g. to build shared libraries
557	on Mac OS X.</li>
558
559	<li>The options with a direct link to hard-process generation
560	in PYTHIA 6 has been removed. It is hardly ever used but
561	complicates the build structure. (Owing to its usefulness for some
562	debug work, it was reinstated in a limited form in version 8.135.
563	Thus <code>main51.cc</code> now contains the complete interface,
564	previously in separate files, and commented-out lines in
565	<code>examples/Makefile</code> suggest how PYTHIA 6 could be linked.)
566	</li>
567
568	<li>New argument to <code>Info::errorMsg(...)</code> allows to
569	show all error messages of a specific kind rather than only the
570	first one, e.g. for initialization.</li>
571
572	<li>Correction in decay table of righthanded Majorana neutrinos.
573	Thanks to Arnaud Ferrari and Vladimir Savinov.</li>
574
575	<li>Correction in expressions in the manual for <i>H^+-</i> couplings
576	to an <i>h^0</i>, <i>H^0</i> or <i>A^0</i> and a <i>W^+-</i>.
577	Thanks to Rikard Enberg.</li>
578
579	<li>Fix for accessing uninitialized memory, caused by accessing the
580	daughters of the incoming beams before these daughters actually existed.
581	Thanks to David Bailey and Sami Kama.
582	</li>
583
584	<li>Uninitialized photon PDF inside the proton could give crazy results
585	for processes with incoming photons. Thanks to Adam Davison.</li>
586
587	<li>Bug fix such that finite lifetimes can be set also for particles
588	produced in the hard process. To exemplify, the bug affected
589	<i>tau</i> leptons produced in <i>Z^0</i> and <i>W^+-</i>
590	decays. Thanks to Troels Petersen.</li>
591
592	<li>Bug fix in <code>TimeShower</code>, that <code>beamOffset</code>
593	could remain uninitialized. Thanks to Sami Kama.</li>
594
595	<li>Minor correction to resonance decays: fail if the allowed mass
596	range of a Breit-Wigner resonance is a small fraction of the total
597	area under the resonance curve.</li>
598
599	<li>Correction when all three valence quarks were kicked out from a
600	proton and could give false messages that beam momentum had been
601	used up.</li>
602
603	<li>Clarify status codes needed for hadron-level standalone runs in
604	order to avoid error messages, and modify the <code>main21.cc</code>
605	example accordingly. </li>
606
607	<li>Minor corrections in the processes for extra dimensions.</li>
608
609	<li>Some other minor additions to existing facilities
610	and minor bug fixes.</li>
611
612	</ul>
613	</li>
614
615	<li>8.135: 10 January 2010
616	<ul>
617
618	<li>All usage of static member methods inside Pythia8 has now been
619	eliminated. This simplifies for you to have several simultaneous
620	<code>Pythia</code> instances that are run with different conditions.
621	The three main classes affected by this are the <code>Settings</code>
622	and <code>ParticleData</code> databases and the <code>Rndm</code>
623	random-number generator. You can no longer address the methods of these
624	classes directly, but have to address them via the <code>settings</code>,
625	<code>particleData</code> and <code>rndm</code> instances in the
626	respective <code>Pythia</code> object. Also some other smaller pieces
627	of code are affected, e.g. Standard Model and SUSY couplings
628	(the latter in new files).
629	<br/><b>Note 1</b>: The documentation has been updated accordingly
630	on these webpages, but the "A Brief Introduction to PYTHIA 8.1"
631	still refers to the old behaviour of version 8.100.
632	<br/><b>Note 2</b>: the interface to the external LHAPDF library remains
633	static, since LHAPDF is written in Fortran and thus by definition
634	static.
635	<br/><b>Note 3:</b> if you want to have momentum smearing in
636	<code>CellJet</code> you now need to send in a pointer to a
637	random-number generator.
638	</li>
639
640	<li>Ten new proton PDF sets are made available internally:
641	MRST LO* (2007), MRST LO** (2008), MSTW 2008 LO (central member),
642	MSTW 2008 NLO (central member), CTEQ6L, CTEQ6L1, CTEQ6.6 (NLO,
643	central member), CT09MC1, CT09MC2, and CT09MCS, see
644	<a href="PDFSelection.html" target="page">PDF Selection</a>. The Pomeron PDF data
645	files have been renamed for consistency. Thanks to Tomas Kasemets
646	for help with this [<a href="Bibliography.html" target="page">Kas10</a>].
647	</li>
648
649	<li>New parameters <code>TimeShower:pTmaxFudgeMPI</code> and
650	<code>SpaceShower:pTmaxFudgeMPI</code> introduced, to give the same
651	functionality for multiparton interactions that
652	<code>TimeShower:pTmaxFudge</code> and <code>SpaceShower:pTmaxFudge</code>
653	do for the hardest.</li>
654
655	<li>A few extensions of the <code>UserHooks</code> framework.
656	New methods <code>UserHooks:canVetoISREmission()</code> and
657	<code>UserHooks::doVetoISREmission(...)</code> allows the latest
658	initial-state emission to be studied before being finalized,
659	with the possibility to veto it.
660	Similarly <code>Userhooks:canVetoFSREmission()</code> and
661	<code>UserHooks::doVetoFSREmission(...)</code> can be used to
662	veto the latest final-state emission.</li>
663
664	<li>A number of loop counters have been introduced in the
665	<code>Info</code> class, that offers some further information on
666	the progress of the event generation, for use e.g. in conjunction
667	with the <code>UserHooks</code> facility.</li>
668
669	<li>The <code>Pythia::initTunes(...)</code> method is made public, so that
670	it can be called before the normal call from <code>Pythia::init(...)</code>.
671	That way it is possible to start out from a given tune and change a few
672	of the parameters.
673	</li>
674
675	<li>Bug corrected in <code>LHAFortran.h</code> for hard-process input
676	from Fortran commonblock. This did not work properly when the input
677	was used in combination with a second hard process generated internally.
678	Thanks to Mikhail Kirsanov and Roberto Chierici.
679
680	<li>Insertion of missing initialization of <code>isInit</code> in the
681	<code>Settings</code> and <code>ParticleData</code> constructors, and
682	<code>nInit</code> for <code>BeamParticle</code>.
683	Thanks to Leif Lönnblad.</li>
684
685	<li>Updated <code>Makefile.msc</code> for Windows users.</li>
686
687	<li>Fix of some non-optimal use of booleans, that give warnings on
688	a Windows compiler. Thanks to Anton Karneyeu.</li>
689
690	<li>New options for the <a href="SUSYLesHouchesAccord.html" target="page">
691	SUSY Les Houches Accord</a> such that, by default,
692	particle and decay data are not overwritten for known Standard Model
693	particles (including <i>Z^0</i>, <i>W^+-</i> and <i>t</i>,
694	but excluding the Higgs).</li>
695
696	<li>Bug fix in <code>SusyLesHouches</code>, where the reading of SLHA
697	information embedded in an LHEF would not stop at the end of the header
698	section.</li>
699
700	<li>Bug correction for undefined secondary widths where decay products
701	together are heavier than the mother. Also unit default secondary width
702	values in the <code>DecayChannel</code> constructor.</li>
703
704	<li>Documentation updated, including change of current year to 2010.</li>
705
706	</ul>
707	</li>
708
709	<li>8.140: 16 July 2010
710	<ul>
711
712	<li>Four new draft <a href="Tunes.html" target="page">tunes</a> available.</li>
713
714	<li>Introduction of a new scenario for production of Hidden-Valley
715	particles, and interleaved showering in the QCD and HV sectors, see
716	the new <a href="HiddenValleyProcesses.html" target="page">Hidden Valleys</a>
717	description. A longer physics writeup is available [<a href="Bibliography.html" target="page">Car10</a>].
718	</li>
719
720	<li>Implementation of <i>2 -> 3</i> phase space selection intended
721	for QCD processes with massless partons. A new set of matching
722	<a href="PhaseSpaceCuts.html" target="page">phase space cut parameters</a>.
723	The <a href="QCDProcesses.html" target="page">ten different QCD <i>2 -> 3</i>
724	processes</a> have been implemented making use of this new
725	possibility, so far without a complete handling of possible colour
726	flows, however.</li>
727
728	<li>New processes have been added for
729	<a href="CompositenessProcesses.html" target="page">contact interactions</a> in
730	<i>q q -> q q</i> and <i>q qbar -> q qbar</i> scattering.</li>
731
732	<li>A process has been added for TeV^-1 Sized
733	<a href="ExtraDimensionalProcesses.html" target="page">Extra Dimensions</a>, which
734	involves the electroweak KK gauge bosons, i.e. <i>gamma_{KK}/Z_{KK}</i>,
735	in one TeV^-1 sized extra dimension; see <code>main30.cc</code> for
736	an example. This scenario is described in [<a href="Bibliography.html" target="page">Bel10</a>]. Thanks to
737	Noam Hod and coworkers for contributing this code.</li>
738
739	<li>In the Randall-Sundrum extra-dimensional scenario a new option has
740	been added where SM fields can exist in the bulk rather than only on
741	a brane. (Still under development.) Furthermore production of a
742	Kaluza-Klein gluon state has been added, and the <code> main28.cc</code>
743	test program extended.</li>
744
745	<li>The scenario for monojets in Large Extra Dimensions has been expanded
746	with an alternative for scalar graviton exchange instead of tensor one.
747	</li>
748
749	<li>New parameters for maximum scale of
750	<a href="TimelikeShowers.html" target="page">timelike showers</a>,
751	<code>TimeShower:pTmaxMatch</code>, and the dampening of hard radiation,
752	<code>TimeShower:pTdampMatch</code> and <code>TimeShower:pTdampFudge</code>,
753	by analogy with corresponding ones for spacelike showers. Also new method
754	<code>TimeShower:limitPTmax(...)</code> to implement alternative procedures.
755	For dipoles stretched to the beam the new switch
756	<code>TimeShower:dampenBeamRecoil</code> allows to dampen radiation
757	close to the beam direction, with a changed default behaviour.</li>
758
759	<li>Azimuthal anisotropies from coherence arguments have been introduced
760	for the spacelike parton showers, see <code>SpaceShower:phiIntAsym</code>
761	and <code>SpaceShower:strengthIntAsym</code>.
762	Also azimuthal anisotropies from gluon polarization have been introduced
763	for the spacelike parton showers, see <code>SpaceShower:phiPolAsym</code>,
764	and updated for timelike parton showers, see
765	<code>TimeShower:phiPolAsym</code>.</li>
766
767	<li>Improvements for the matching to POWHEG LHEF-style input illustrated
768	by the new <code>main71.cc</code> example. See also [<a href="Bibliography.html" target="page">Cor10</a>].</li>
769
770	<li>A set of new processes <i>gamma gamma -> f fbar</i>, with <i>f</i>
771	quarks or leptons. Code for equivalent photon flux around an unresolved
772	proton, with more to come. Thanks to Oystein Alvestad.
773	</li>
774
775	<li>A new option has been included to dampen the growth of the diffractive
776	cross sections, see <a href="TotalCrossSections.html" target="page">Total Cross
777	Sections</a>.</li>
778
779	<li>A new method <code>virtual int SigmaProcess::idSChannel()</code>
780	has been introduced. If overloaded to return a nonzero value then a
781	<i>2 -> n</i> process will appear listed as a <i>2 -> 1 -> n</i> one.
782	That is, an intermediate resonance with the requested identity will be
783	inserted in the event record, even without appearing in the calculation
784	of the matrix element proper. Thanks to Noam Hod for idea and code.</li>
785
786	<li>A new method <code>SigmaProcess::convertM2()</code> has been introduced
787	to optionally allow the <code>SigmaProcess::sigmaHat()</code> to return
788	the squared matrix element rather than <i>d(sigmaHat)/d(tHat)</i> for
789	<i> 2 -> 2 </i> processes. Furthermore kinematics is stored in the new
790	<code>mME</code> and <code>pME</code> vectors for alternative cross
791	section encodings.</li>
792
793	<li>Different encoding of the <i>f fbar -> Z W</i> cross section,
794	contributed by Merlin Kole, based on the cross section of
795	Brown, Sahdev and Mikaelian. Gives a distinctly different cross section
796	than the previous based on EHLQ (including their bug fix).
797	In particular the problem with negative cross sections is now fixed.</li>
798
799	<li>Minor updates: pass <code>xmlPath</code> to new MSTW and CTEQ PDFs;
800	reset beams earlier to give cleaner documentation.</li>
801
802	<li>The H1 Fit B LO parametrization to the Pomeron PDF has been included,
803	and made new default for Pomerons. Thanks to Paul Newman for providing
804	the data files.</li>
805
806	<li>Three changes, in principle unrelated, but with the common objective
807	to make the generation of a given event depend only on the values
808	determined during the initialization stage and on the state of the
809	random-number generator when the event is begun. The new default
810	should ensure a reproducible stop-and-restart behaviour, convenient
811	for debug purposes. Thanks to Michael Schmelling for stressing the
812	desire for such a behaviour.
813	<br/>(i) Introduction of a new option <code><a href="PhaseSpaceCuts.html" target="page">
814	PhaseSpace:increaseMaximum</a></code> that allows to switch between
815	two strategies for handling the (hopefully rare) cases when the
816	assumed maximum of the cross section function is exceeded during the
817	event generation, with a changed default behaviour. In the old
818	default the maximum could be increased if it was exceeded during the run,
819	thereby introducing a memory of the previously generated events.
820	<br/>(ii) Updated handling of random numbers with Gaussian distributions.
821	The <code>gauss()</code> method now only generates one value at a time.
822	Instead the new <code>gauss2()</code> method returns a pair of Gauss
823	numbers, with related time savings. In the old approach one Gaussian
824	number could be buffered, which introduced a memory.
825	<br/>(iii) Minor bug fix in <code>MiniStringFragmentation</code>, where
826	the popcorn baryon state was not reset for each new system, again
827	giving a (flawed) memory.</li>
828
829	<li>New directory <code>rootexample</code> with a simple code example
830	how to use ROOT for histogramming in PYTHIA runs. See
831	<a href="ROOTusage.html" target="page">ROOT Usage</a> for details. Thanks to Rene Brun.
832	</li>
833
834	<li>In the <code>HepMCinterface</code> the checks for unhadronized
835	quarks and gluons are not performed if hadronization has been switched
836	off.</li>
837
838	<li>The <code>UserHooks::initPtr(...)</code> has been expanded so that
839	pointers to more classes (beam particles, random number, couplings, etc.)
840	are sent in, thereby increasing the scope of possible user-written code.
841	Also, the <code>UserHooks::doVetoProcessLevel(Event& process)</code>
842	now allows the <code>process</code> event record to be modified,
843	even if it is not recommended. The new <code>Info::pTnow()</code>
844	method returns the current <i>pT</i> scale of the combined MPI, ISR
845	and FSR evolution, which can be useful for some user hooks decisions.
846	</li>
847
848	<li>Histograms of the <code>Hist</code> class can now be booked
849	with up to 1000 bins, instead of the previous maximum 100. All bins
850	can be written to file, but the line-printer style printing will join
851	nearby bins so at most 100 are printed, as before. </li>
852
853	<li>Updated <code>configure</code> and <code>Makefile</code>
854	to allow 64-bit compilation and more options. Thanks to Mikhail Kirsanov,
855	Rene Brun and Fons Rademakers.</li>
856
857	<li>Bug fix in <code>ProcessLevel</code> for colour flow checks of
858	junctions. Enables the decay of a neutralino to three quarks, e.g.
859	Thanks to Nils-Erik Bomark.</li>
860
861	<li>Bug fixes in <code>TimeShower</code>, where recoil partners in resonance
862	decays of coloured particles, and recoil partners in QED dipoles when beams
863	are not allowed to take a recoil, might not be correctly identified. </li>
864
865	<li>Bug fix in <code>SpaceShower</code>: when used with a fixed
866	<i>alpha_strong</i>, the threshold enhancement factor of
867	<i>g -> Q Qbar</i> became undefined. Thanks to Stefan Prestel.</li>
868
869	<li>Bug fix in initialization of resonance widths, where the
870	<code>minWidth</code> parameter could be used uninitialized,
871	occasionally resulting in strange initialization problems when
872	kinematics needs to force at least one resonance to be off-shell.</li>
873
874	<li>Minor updates of <code>main06.cc</code>, <code>main10.cc</code>
875	and <code>main23.cc</code>.</li>
876
877	<li>Bug fix in mother pointer of multiparton interactions in
878	diffractive systems.</li>
879
880	</ul>
881	</li>
882
883	<li>8.142: 15 August 2010
884	<ul>
885
886	<li>The strategy for setting up tune values has been changed.
887	Previously the <code>Tune:ee</code> and <code>Tune:pp</code>
888	settings were only interpreted during the
889	<code>Pythia::init(...)</code> stage. Now they are interpreted
890	as soon as they are read. Specifically this means that it is
891	possible to override any of the tune parameters by putting new
892	commands below <code>Tune:ee</code> and <code>Tune:pp</code>
893	in the <code>Pythia::readFile(...)</code> configuration file
894	or in the list of <code>Pythia::readString(...)</code> commands.
895	<br/>As a consequence of this change, the public
896	<code>Pythia::initTunes(...)</code> method has been replaced by
897	two private <code>Settings::initTuneEE(...)</code> and
898	<code>Settings::initTunePP(...)</code> methods.
899	<br/>If <code>Tune:ee</code> or <code>Tune:pp</code> are
900	nonvanishing by default, then the corresponding tune variables
901	are set also from the <code>Pythia</code> constructor, before any
902	user changes are possible. Currently this is not relevant.
903	</li>
904
905	<li>Bug fix in the setup of the <code>Tune:pp = 5</code> and
906	<code>= 6</code> options, which meant that diffractive cross
907	sections were not reduced as advertised.</li>
908
909	<li>The default value of <code>MultipartonInteractions:pT0Ref</code>
910	has been slightly reduced so as to give a somewhat improved
911	default description. It is not intended as a replacement for the
912	specific tunes, however.</li>
913
914	<li>Some comparisons between tunes and data, obtained with the
915	Rivet package, have been posted on
916	<a href="http://home.thep.lu.se/~richard/pythia81/">
917	http://home.thep.lu.se/~richard/pythia81/</a>.
918	Further improvements can be expected from future Professor-based
919	tunes. The current set of 2C, 2M, 3C and 3M "draft tunes" have
920	deliberately been chosen different also to explore a range of
921	possibilities. One not visible in the plots is the fraction
922	of single and double diffractive events in the inelastic cross
923	section. This is 32% in 2C and 2M, while it was reduced to
924	21% in 3C and 3M, and a recent ATLAS study (ATLAS-CONF-2010-048)
925	would suggest 28+-4%.</li>
926
927	<li>Minor changes in <code>TimeShower</code> and
928	<code>SpaceShower</code>, as protection if the <i>c</i> or
929	<i>b</i> masses are set small.</li>
930
931	<li>Bug fix in <code>SpaceShower</code>, for case when <i>phi</i>
932	angle selection is biased to take into account interference effects.
933	</li>
934
935	<li>The <code>SigmaProcess::convertM2()</code> method now has
936	been implemented also for <i>2 -> 1</i> processes, so that it is
937	possible to provide the squared matrix element instead of
938	<i>sigmaHat</i> for semi-internal processes. A fixed-width
939	Breit-Wigner is also inserted, since the matrix element is supposed
940	not to include it.</li>
941
942	<li>New method <code>SigmaProcess::setupForME()</code> does an
943	extended conversion from the internal kinematics to an almost
944	equivalent one, better adapted to the mass conventions of matrix-element
945	caclulation programs, such as massive incoming <i>b</i> quarks.
946	New flags allow to determine whether the <i>c</i>, <i>b</i>,
947	<i>mu</i> and <i>tau</i> should be considered massless or not
948	in the calculations.</li>
949
950	<li>Two new friend methods <code>table</code> of the <code>Hist</code>
951	class allow to print a table with three columns, the first for the
952	(common!) <i>x</i> values and the other two for the respective
953	histogram values. A new method <code>takeSqrt</code> for the square
954	root of histogram bin contents.
955	</li>
956
957	</ul>
958	</li>
959
960	<li>8.145: 10 November 2010
961	<ul>
962
963	<li><code>Couplings</code> is defined in <code>StandardModel.h</code>
964	as a derived class of <code>coupSM</code> and has only one extra flag:
965	<code>isSUSY</code> to check presence of extra couplings.Changed all
966	pointers <code>CoupSM</code> to <code>Couplings</code> and removed
967	explicit references to <code>CoupSUSY*</code>. The <code>coupSUSY</code>
968	object is only initialised if SUSY couplings are present. The new pointer
969	<code>couplingsPtr</code> points either to only SM couplings or SM+SUSY
970	couplings based on SLHA data.</li>
971
972	<li>New files <code>SusyResonanceWidths.h/cc</code> contains the
973	<code>SusyResonanceWidths</code> class, which inherits from
974	<code>ResonanceWidths</code> but typecasts the <code>couplingsPtr</code>
975	to <code>(CoupSUSY*) coupSUSYPtr</code>. This is the base class for
976	all SUSY resonances. It contains the <code>ResonanceSquark</code> class
977	for all squark decays. A new flag <code>SLHA:useDecayTable</code>
978	to check if internal widths should be overwritten by those read in
979	via SLHA.</li>
980
981	<li>Added new functionality to <code>SusyLesHouches</code> for read-in
982	of generic user blocks in the SLHA format, along with methods to
983	extract parameters from them with typecasting controlled by the user.
984	Intended for use with user-written semi-internal processes.</li>
985
986	<li>Added <code>Sigma1qq2antisquark</code> cross section.</li>
987
988	<li>Some new flags and modes in the <code>SUSY</code> and
989	<code>SLHA</code> series offer further functionality.</li>
990
991	<li>Several further changes as a consequence of the upgrade of the SUSY
992	machinery.</li>
993
994	<li>Bug/typo fixes in rotation matrices for SUSY couplings and for the
995	processes <code>qqbar2squarkantisquark</code>,
996	<code>qq2squarksquark</code> and more.</li>
997
998	<li>Improved handling of colour junctions. Added new example program
999	<code>main72.cc</code>, to illustrate read-in of color junction
1000	structures via LHEF (<code>main72.lhe</code>). The example used is SUSY
1001	with RPV.</li>
1002
1003	<li>New Tune 4C introduced as <code>Tune:pp = 5</code>. The more crude
1004	(non-)tunes 3C and 3M are removed.</li>
1005
1006	<li>New methods <code>Settings::getFlagMap(...)</code>,
1007	<code>Settings::getModeMap(...)</code>,
1008	<code>Settings::getParmMap(...)</code> and
1009	<code>Settings::getWordMap(...)</code> allows to return a map of all
1010	settings of the respective type that contain a specific string
1011	in its name.
1012	</li>
1013
1014	<li>Improved description of excited <i>g^/KK-gluon^</i> production
1015	in the <code>Sigma1qqbar2KKgluonStar</code> and
1016	<code>ResonanceKKgluon</code> classes.</li>
1017
1018	<li>Possibility added to let Hidden-Valley <i>gamma_v</i> have
1019	a nonero mass and decay by mixing with the ordinary photon.
1020	Still experimental.</li>
1021
1022	<li>Minor bug fix in handling of three-body phase space.</li>
1023
1024	<li>Minor correction in <code>Sigma2ffbar2TEVffbar</code> class.</li>
1025
1026	<li>Bug fix for decays of <i>W'</i> to a pair of heavy fermions when
1027	<i>gV != gA</i>. Thanks to M. Chizhov, see arXiv:0705.3944. </li>
1028
1029	<li>Restore the older EHLQ-based encoding of the <i>f fbar -> Z W</i>
1030	cross section, which was changed in version 8.140, since comparisons
1031	with Madgraph gives much better agreement with it than with the
1032	expression of Brown, Sahdev and Mikaelian.</li>
1033
1034	<li>The <code>HepMCInterface</code> now also stores colour flow
1035	information for coloured particles.</li>
1036
1037	<li>Pointer to <code>Couplings</code> made available for particle
1038	decays.</li>
1039
1040	<li>Minor update in <code>main61.cc</code> for more elegant usage
1041	of FastJet, as suggested by Gregory Soyez.</li>
1042
1043	</ul>
1044	</li>
1045
1046	<li>8.150: 20 April 2011
1047	<ul>
1048
1049	<li>Tune 4C is made default. It is based on first comparisons with
1050	LHC data [<a href="Bibliography.html" target="page">Cor10a</a>], and has also been checked independently
1051	[<a href="Bibliography.html" target="page">Buc11</a>] to give reasonable agreement with many distributions.
1052	</li>
1053
1054	<li>The description of <i>tau</i> lepton decays has been significantly
1055	enhanced, to include helicity information related to the production
1056	process and hadronic currents fitted to data. A complete writeup is
1057	in preparation [<a href="Bibliography.html" target="page">Ilt11</a>]. A new flag is introduced to revert
1058	to the old behaviour, for cross-checks, see
1059	<a href="ParticleDecays.html" target="page">Particle Decays</a>.
1060	The new tau decay machinery is on by default.
1061	</li>
1062
1063	<li>A new option <code>MultipartonInteractions:bProfile = 4</code> has
1064	been introduced for the impact-parameter profile of protons in the
1065	<a href="MultipartonInteractions.html" target="page">Multiparton Interactions</a>
1066	framework, wherein low-<i>x</i> partons are spread over a larger area
1067	than high-<i>x</i> ones, see [<a href="Bibliography.html" target="page">Cor11</a>]. A new method
1068	<code>Info::eMPI(i)</code> gives back the enhancement factor related to
1069	the <code>i</code>'th interaction. The impact-parameter profile can now
1070	be selected separately for <a href="Diffraction.html" target="page">diffraction</a>,
1071	but without a <code>bProfile = 4</code> option.
1072	</li>
1073
1074	<li>The possibility of "hadronization" in the
1075	<a href="HiddenValleyProcesses.html" target="page">Hidden Valley</a> sector
1076	has been added as a new option <code>HiddenValley:fragment = on</code>.
1077	This is based on a copy of the standard string fragmentation framework,
1078	but with the option of a completely separate "flavour" sector, and
1079	separately tunable longitudinal fragmentation functions and transverse
1080	momenta. For now only a simple flavour scenario is provided, where
1081	flavour-diagonal mesons can decay back into the normal visible sector
1082	while off-diagonal ones remain hidden. A writeup of the model is in
1083	preparation [<a href="Bibliography.html" target="page">Car11</a>]. Also some further Hidden Valley options
1084	have been added.</li>
1085
1086	<li>Included possibility in <code>TimeShower</code> for QCD dipoles to
1087	have an adjustible normalization factor, via the new
1088	<code>bool isFlexible</code> and <code>double flexFactor</code>
1089	properties of <code>class TimeDipoleEnd</code>. This flexibility is used
1090	to treat radiation off colour topologies with epsilon tensors, in
1091	particular colour junctions which have all their partons in the
1092	final state. (An example is the BNV-SUSY decay ~chi0→uds.) For
1093	such topologies, the new treatment in PYTHIA 8 is that a
1094	half-strength dipole is spanned between all combinations of
1095	final-state quarks. For junctions with an incoming (anti)colour line (such
1096	as in the BNV-SUSY decay ~t*→cb), a full-strength dipole is
1097	instead spanned between the two daughters, with no radiation from the
1098	decaying object (in its CM). As will be described in a fortcoming
1099	paper with N. Desai, this should give the
1100	closest possible correspondence to the radiation patterns exhibited
1101	by higher-order matrix elements for this type of process.</li>
1102
1103	<li>Corrected harmless bugs in <code>ProcessLevel::findJunctions</code>
1104	which caused junctions of types 3 and 4 (i.e., junctions with 1
1105	incoming color tag) to sometimes be incorrectly classified as types
1106	1 and 2 (with all color tags outgoing), respectively.
1107	Since the parity (even/odd) of the junction kind was still correct,
1108	however, this did not cause any problems at the hadronization
1109	stage.</li>
1110
1111	<li>The junction-finder in <code>ProcessLevel::findJunctions</code>
1112	has been made more stable, and the following ordering of the color
1113	tags returned by <code>Event::endColJunction(iJun, iLeg)</code> is
1114	now enforced: for junction kinds 3 and 4 (one tag
1115	incoming), <code>iLeg = 0</code> will return the
1116	incoming tag, while for kinds 5 and 6 (two tags incoming),
1117	<code>iLeg = 0</code> and <code>iLeg = 1</code> will return the
1118	incoming tags. Apart from this ordering, the color tags are
1119	ordered in ascending color tag number.</li>
1120
1121	<li>Declarations of friend functions moved to sit outside the class
1122	it befriends. Thanks to Axel Naumann for pointing out the incorrect
1123	previous construction.</li>
1124
1125	<li>The <code>rootexample</code> subdirectory becomes
1126	<code>rootexamples</code> as the old example is split into two,
1127	with improved documentation to clarify usage. Thanks to Axel Naumann
1128	and Bernhard Meirose for the new code.</li>
1129
1130	<li>In the Les Houches Event File machinery, input type has been
1131	changed from <code>ifstream</code> to <code>istream</code> for more
1132	flexibility.</li>
1133
1134	<li>R-hadron handling is largely implemented, see the
1135	<a href="RHadrons.html" target="page">R-hadrons</a> page, although some aspects
1136	still need polishing. A new class <code>RHadrons</code> takes
1137	care of the hadronization and decay. Particle data have been added
1138	for R-hadrons containing a gluino, stop or sbottom, but could
1139	alternatively be used for other long-lived coloured particles.
1140	Thanks to Bernhard Meirose for support.
1141	</li>
1142
1143	<li>Calculations of SUSY decay widths included by
1144	N. Desai, contained in the new source
1145	files <code>SusyResonanceWidth.cc</code>
1146	and </code>.h</code>. Validation and addition of more modes is still in
1147	progress, so this implementation should be considered preliminary
1148	for now. For a list of available modes, see
1149	the <a href="SUSYProcesses.html" target="page">SUSY Processes</a> page.
1150	</li>
1151
1152	<li>A first implementation of the SLHA-based QNUMBERS interface for
1153	defining new exotic particles has been
1154	included. See [<a href="Bibliography.html" target="page">Alw07</a>] and
1155	the <a href="SUSYLesHouchesAccord.html" target="page">SUSY Les Houches Accord</a>
1156	page. </li>
1157
1158	<li>Read-in of LHEF events containing Baryon Number Violating vertices
1159	has been included, using colour junctions, see
1160	the <a href="EventRecord.html" target="page">Event Record</a> page. The advanced
1161	shower model taking into account the full colour structure of such
1162	events, developed by N. Desai and described above,
1163	is turned on by default in such events.
1164	Several test cases were used to
1165	validate this implementation, but it is possible that problems could
1166	still exist for some cases. Feedback is welcome. Thanks to
1167	the MadGraph authors for providing several test cases.</li>
1168
1169	<li>Some first steps taken to allow events containing colour sextets,
1170	e.g., from semi-internal processes or LHEF interfaces, and/or from
1171	SLHA <code>DECAY</code> tables. New
1172	<code>colType</code> codes 3 and -3 are introduced to describe
1173	sextets and antisextets, respectively. The state of the current
1174	implementation is that hard processes containing such states can be
1175	read in and decays generated (via <code>DECAY</code> tables). Parton
1176	showers can be added, but the sextets themselves do not, as yet,
1177	shower, and any undecayed sextets remaining at the hadronization
1178	stage would lead to unpredictable problems if hadronization is
1179	switched on. Thanks to J. Alwall for help with testing
1180	this implementation.
1181	</li>
1182
1183	<li>The functionality of the SLHA SUSY/BSM interface (see
1184	the <a href="SUSYLesHouches.html" target="page">SUSY Les Houches</a> page) has been
1185	extended so that copies of all <code>BLOCK</code>s are now stored
1186	internally as
1187	strings, regardless of whether they correspond to "official" SLHA
1188	blocks or not. Their contents can subsequently be queried by a set
1189	of new templated member functions of the
1190	class <code>SusyLesHouches</code>. Available query functions so far
1191	include
1192	<br/><code>template <class T> bool getEntry(string, T&);</code>,
1193	<br/><code>template <class T> bool getEntry(string, int, T&);</code>,
1194	<br/><code>template <class T> bool getEntry(string, int, int, T&);
1195	</code>, and
1196	<br/><code>template <class T> bool getEntry(string, int,
1197	int, int, T&);</code>,
1198	<br/>where the type of
1199	the argument used in the call determines how to read the block
1200	entries. Thus, if an LHEF, SLHA, or other card file is read in by
1201	PYTHIA, the contents of any <code>BLOCK</code> in that file can
1202	subsequently be queried run-time using these functions. This is
1203	used, e.g., in the new interface between MADGRAPH 5 and PYTHIA
1204	8. Thanks to the MADGRAPH team, and to J. Alwall in particular, for
1205	help and debug on this new implementation.
1206	</li>
1207
1208	</ul>
1209	</li>
1210
1211	<li>8.153: 10 August 2011
1212	<ul>
1213
1214	<li>The setup of tunes has been modified, see the
1215	<a href="Tunes.html" target="page">Tunes</a> page for details. Specifically
1216	the <code>Tune:ee</code> and <code>Tune:pp</code> modes have
1217	acquired a new option <code>-1</code> for a forced restore to the
1218	default values of all settings used in the respective kind of
1219	tunes.</li>
1220
1221	<li>The code for handling multiparton interactions in the scenario with
1222	an <i>x</i>-dependent width of the Gaussian matter profile
1223	[<a href="Bibliography.html" target="page">Cor11</a>], has been improved and updated. Tune 4Cx, which
1224	is based on this option, has been added as a further tune option.</li>
1225
1226	<li>A possibility to bias the phase-space selection has been added,
1227	whereby some phase space regions can be oversampled, which is
1228	compensated by assigning a weight to each event.
1229	A new set of methods have been added to the <code>UserHooks</code>
1230	class to allow users to program how to bias the selection.</li>
1231
1232	<li>New options added so that matrix-element corrections can be
1233	switched off after the first branching in ISR or FSR.</li>
1234
1235	<li>Some new <code>Info</code> methods have been added to store
1236	information on latest ISR branching. The <code>SpaceShower</code>
1237	class has also been corrected so that the latest <i>z = 1/2</i>
1238	when not defined by history. This avoids undefined values for
1239	azimuthal asymmetries. Thanks to Stefan Prestel for finding and
1240	sorting out this problem.</li>
1241
1242	<li>The <code>Pythia::forceHadronLevel()</code> method now takes
1243	an argument that optionally means that existing junction information
1244	is not overwritten. Thanks to Leif Lönnblad for pointing out
1245	the usefulness of this.</li>
1246
1247	<li>For particle decays to a varying number of hadrons the multiplicity
1248	increase with mass has been somewhat reduced, and especially for
1249	<code>meMode = 23</code> a separate even slower increase has been
1250	introduced.</li>
1251
1252	<li>New possibility to force the tau polarization.</li>
1253
1254	<li>Bug fix for the special case in which events containing SUSY
1255	particles are generated without proper initialization of SUSY decays.
1256	This can happen, e.g., if events containing SUSY particles are read
1257	in via external LHEF files, if those files do not contain readable
1258	SLHA spectra in their headers. In this case, a failed attempt to
1259	generate sparticle decays with ill-defined couplings previously
1260	led to crashes. The program now reverts to the old behaviour,
1261	based on static decay tables, in such cases, with the default
1262	being to decay all sparticles to gravitino + particle. An error
1263	message stating that the full SUSY treatment has been switched
1264	off and why is also issued. Thanks to N. Desai for this fix.</li>
1265
1266	<li>The R-hadron machinery has been completed.</li>
1267
1268	<li>Minor change in timelike showers: gluons which fall below the
1269	<i>pTmin</i> cutoff by the correction for mass effects are now
1270	eliminated, while previously they were kept. This reduces the
1271	number of gluons somewhat, but has no significant effects on the
1272	hadronic final state. (Prompted by R-hadron studies, where big mass
1273	effects else give bothersome low-energy gluons.)</li>
1274
1275	<li>Corrected typos in two of the Upsilon wave function matrix
1276	elements, <code>Bottomonium:OUpsilon3P08</code> and
1277	<code>Bottomonium:Ochib03P01</code>. Thanks to Beate Heinemann for
1278	pointing it out.</li>
1279
1280	<li>Implemented <i>f</i> decay angle in <i>f f -> f f</i> processes,
1281	and fixed some bugs for the same process. Thanks to Piyali Banerjee
1282	for tests.</li>
1283
1284	<li>Introduce possibility to separate production channels for
1285	TeV-sized extra dimensions, and a small code correction. Thanks to
1286	Noam Hod for code contribution.</li>
1287
1288	<li>Bug fix for neutrino beams: since neutrinos are always lefthanded
1289	there should be a factor 2 in the cross section, relative to charged
1290	leptons, from the non-need to average over incoming spin states. This
1291	is now fixed by introducing a new PDF class <code>NeutrinoPoint</code>
1292	for (unresolved) neutrinos, with normalization 2 rather than 1 for
1293	charged leptons. Thanks to Ryosuke Sato.</li>
1294
1295	<li>Bug fix for some (rarely used) particle settings, which could not
1296	be changed by users because they were read too early. Thanks to
1297	Andrew Altheimer and Gustaaf Brooijmans.</li>
1298
1299	<li>Bug fix in handling of <code>tau</code> decays, where setting of
1300	decay vertices could write outside memory. Thanks to Steven Schramm.</li>
1301
1302	<li>Minor expansion of the <code>BeamParticle</code> constructor.</li>
1303
1304	<li>Minor bug fix in CTEQ 6L for uninitialized variables.</li>
1305
1306	<li>Minor bug fix in fragmentation flavour combination to hadron.</li>
1307
1308	<li>Some updates of the documentation, including new pages on
1309	MadGraph 5 as a generator for semi-internal processes (thanks to
1310	Johan Alwall) and on RIVET interfacing.</li>
1311
1312	<li>Minor improvements of ROOT- and HepMC-related code and documentation.</li>
1313
1314	<li>Some cleanup of code.</li>
1315
1316	</ul>
1317	</li>
1318
1319	<li>8.157: 10 November 2011
1320	<ul>
1321
1322	<ii>StefanPrestel joins as new member of the PYTHIA author team.
1323	He is mainly working on matching/merging issues, and has contributed
1324	the CKKW-L machinery mentioned below.</li>
1325
1326	<li>Merging capabilities according to the CKKW-L scheme [<a href="Bibliography.html" target="page">Lon11</a>]
1327	have been added, see the new
1328	<a href="MatrixElementMerging.html" target="page">Matrix Element Merging</a>
1329	page. It involves new classes to reconstruct and select how a
1330	matrix-element-generated partonic configuration could have been obtained
1331	by the PYTHIA evolution, and to perform trial showers (using a new
1332	copy of the normal parton-level machinery) that introduce the appropriate
1333	Sudakov suppression factors. New examples to illustrate various
1334	common tasks are found in <code>main81.cc</code>, <code>main82.cc</code>,
1335	<code>main83.cc</code> and <code>main84.cc</code>.</li>
1336
1337	<li>The <code>main71.cc</code> program is now generalised for reading
1338	in arbitrary POWHEG LHE files, to implement a smooth matching between NLO
1339	matrix elements and the PYTHIA parton showers. Cuts are made on both
1340	ISR and FSR emissions, while previously only ISR was covered. The key
1341	assumptions are the <i>pT</i> definitions used for ISR and FSR, but several
1342	further options are available, as documented in the <code>main71.cmnd</code>
1343	file. Work is still ongoing to pick the best default options. </li>
1344
1345	<li>Several expansions of the <code>UserHooks</code> class.
1346	For both <code>doVetoFSREmission</code> and <code>doVetoISREmission</code>
1347	a new argument <code>iSys</code> labels the system within which the
1348	radiation occurs. For <code>doVetoFSREmission</code> a further argument
1349	<code>inResonance</code> distinguishes FSR in resonance
1350	decays from that in the hard process itself. New methods
1351	<code>canVetoMPIEmission</code> and <code>doVetoMPIEmission</code>
1352	have been added to veto multiparton interactions in the same way as
1353	FSR and ISR. In <code>biasSelectionBy</code> at times incorrect values
1354	for <code>inEvent</code> has been corrected. Also some systematization
1355	of the use of <code>const</code>.</li>
1356
1357	<li>A new model for hadron scattering is introduced, still at an early
1358	stage and therefore more intended for internal development than for the
1359	normal user. The basic idea is that a high-energy <i>pp</i> collision
1360	involves the fragmentation of multiparton strings that overlap in space
1361	(and time). Also the produced hadrons therefore initially overlap, and
1362	there is a strong likelihood that hadrons can scatter against each other
1363	until the system has expanded sufficiently. This can e.g. increase the
1364	transverse momentum of heavier hadrons at the expense of lighter ones.
1365	</li>
1366
1367	<li>A new jet finder <code>SlowJet</code> offers simple access to the
1368	inclusive <i>kT</i>, anti-<i>kT</i>, and Cambridge/Aachen
1369	algorithms in a cylindrical coordinate frame. The jet reconstruction
1370	is then based on sequential recombination with progressive removal,
1371	using the <i>E</i> recombination scheme. The minimalistic
1372	<code>SlowJet</code> code is much slower than <code>FastJet</code>
1373	[<a href="Bibliography.html" target="page">Cac06</a>], and contains less options, but reconstructs the same
1374	jets if run under identical conditions. For details see the
1375	<a href="EventAnalysis.html" target="page">Event Analysis</a> page.</li>
1376
1377	<li>Starting in gcc 4.6, it is possible to switch off specific warnings
1378	around specific blocks of code. Although version 4.6 is some way off
1379	from being commonly found, this option has now been introduced to switch
1380	off <code>-Wshadow</code> warnings in <code>HepMCInterface.cc</code>.
1381	For other compilers, or earlier versions of gcc, the old behaviour
1382	is retained.</li>
1383
1384	<li>Support for reading in gzipped LHEFs has been added in the
1385	<code>LesHouches</code> and <code>SusyLesHouches</code> classes.
1386	This also affects <code>configure</code> and <code>Makefile</code>s.
1387	Unless explicitly enabled, it should not affect anything.
1388	If enabled, it relies on the Boost and zlib libraries to function,
1389	so paths to these must be set appropriately, see the
1390	<code>README</code> file for details. The Boost header files can
1391	give very many shadow warnings, so <code>-Wshadow</code> is disabled
1392	if gzip support is enabled, as described above.</li>
1393
1394	<li>Introduce use of the <code>HEPMC_HAS_UNITS</code> environment
1395	variable in the <code>HepMCInterface.cc</code> and <code>main32.cc</code>
1396	codes to automatically check whether GeV and mm can be set as relevant
1397	units. If yes, then it is set in <code>main32.cc</code>. If no,
1398	a conversion from GeV to MeV is done explicitly in
1399	<code>HepMCInterface.cc</code>. Note that, for early HepMC versions,
1400	this means a change of behaviour. Thanks to Andy Buckley.</li>
1401
1402	<li>A new method <code>Info::lhaStrategy()</code> returns the
1403	Les Houches event weighting strategy where relevant, and 0 where not.
1404	For the strategies <i>+-4</i> the event weight and sum,
1405	<code>Info::weight()</code> and <code>Info::weightSum()</code>,
1406	is now in units of pb at output, as it should be at input.
1407	(While internally mb is used.)</li>
1408
1409	<li>New flag <code>Check:abortIfVeto</code> allows the user to
1410	resume control over execution in case of a veto in the event
1411	generation process.</li>
1412
1413	<li>New method <code>Event::at(i)</code> returns reference to
1414	<code>i</code>'th particle in the event record.</li>
1415
1416	<li>Introduce the Fermi constant as one of the Standard Model
1417	parameters.</li>
1418
1419	<li>Included automatic pre-initialization of SLHA blocks MASS and
1420	SMINPUTS using PYTHIA's SM parameters and particle data table
1421	values.</li>
1422
1423	<li>SUSY: added sleptons (and sneutrinos) as resonances.
1424	Corrected 2-body decay widths of gluinos, squarks and gauginos.
1425	Added sleptonic decay modes to gaugino decays.
1426	Implemented 2-body decays of sleptons (and sneutrinos)
1427	into sleptons/leptons/gauginos. Corrected slepton couplings (they
1428	now look exactly like squark couplings, using a 6x6 slepton mixing
1429	matrix).</li>
1430
1431	<li>New parameter <code>Diffraction:probMaxPert</code> introduce to
1432	give more flexibility in transition from a nonperturbative to a
1433	perturbative description of a diffractive system.</li>
1434
1435	<li>Bug corrected in <code>SigmaEW.cc</code>, for the process
1436	<code>WeakSingleBoson:ffbar2ffbar(s:gm)</code>. Previously, all outgoing
1437	quark flavours in this process were erroneously assigned ID code 5
1438	(b quarks). This has now been corrected so the proper ratios are
1439	obtained, with <i>u : c : d : s : b = 4 : 4 : 1 : 1 : 1</i>,
1440	according to the squared quark charges.</li>
1441
1442	<li>Changes in <code>FragmentationSystems</code> and
1443	<code>StringFragmentation</code> to reject systems with three or more
1444	interconnected junctions. This may happen in baryon-number-violating
1445	scenarios in pp collisions, if both of the beam baryon junctions are
1446	resolved and get connected via an antijunction created by a
1447	hard-process BNV vertex. In principle, this could be addressed by an
1448	extension of the existing junction fragmentation framework. However,
1449	since it happens rarely, for the time being an error message is printed
1450	and the fragmentation restarted.
1451	</li>
1452
1453	<li>Change in <code>Event::copy</code> to safeguard against attempting
1454	to copy out-of-range entries. An attempt to copy a non-existing entry
1455	will now return -1.</li>
1456
1457	<li>Bug fix in the machinery for the user to force the setting of
1458	tau polarization.</li>
1459
1460	<li>Bug fix in the initial search for a maximum of the process
1461	cross section (only affecting rare cases).</li>
1462
1463	<li>Corrected angular decay distributions for two compositeness
1464	processes, <code>Sigma2qq2qStarq</code> and
1465	<code>Sigma2qqbar2lStarlbar</code>.</li>
1466
1467	<li>Extra check in <code>HiddenValleyFragmentation</code> to make sure
1468	that pointers which have not been assigned with <code>new</code> are not
1469	deleted.</li>
1470
1471	<li>Some further minor changes.</li>
1472
1473	</ul>
1474	</li>
1475
1476	<li>8.160: 23 January 2012
1477	<ul>
1478
1479	<li>The older term "multiple interactions" has been replaced by the
1480	new standard "multiparton interactions" one, and correspondingly the
1481	abbreviation MI by MPI. This affects everything: settings, class and
1482	method names, documentation, etc. It therefore becomes necessary to
1483	rewrite user code. However, so as to keep the immediate effort at a
1484	reasonable level, the old settings names are kept as aliases. Thus
1485	<code>PartonLevel:MI</code> and <code>PartonLevel:MPI</code> are
1486	equivalent, and similarly <code>MultipleInteractions:pT0Ref</code>
1487	and <code>MultipartonInteractions:pT0Ref</code>. Should you be using
1488	methods such as <code>double Info::pTMI(int i)</code> you need to
1489	edit the code, however. All the <code>example/main*</code> files
1490	have been uopdated accordingly.</li>
1491
1492	<li>A new option <code>Beams:frameType = 5</code> has been added
1493	for the case where an external generator should provide LHA process
1494	information. The new <code>Pythia::setLHAupPtr(...)</code> method
1495	should then be used to link in this generator. The new switch
1496	<code>Beams:newLHEFsameInit</code> can be used to tell that a new
1497	LHEF should be used, but without the need for a new initialization.
1498	With these two changes, all the different ways of initializing
1499	can be covered by the <code>Pythia::init()</code> call with no
1500	arguments. The various <code>init(...)</code>options with arguments
1501	are deprecated and will be removed for PYTHIA 8.2.</li>
1502
1503	<li> The <code>Pythia::stat()</code> method, with no arguments,
1504	replaces <code>Pythia::statistics(...)</code>, although the latter
1505	remains as a deprecated alternative.</li>
1506
1507	<li>New settings <code>Init:...</code>, <code>Next:...</code>,
1508	and <code>Stat:...</code> can be used to steer some details of
1509	the operation of the <code>Pythia::init()</code>,
1510	<code>Pythia::next()</code> and <code>Pythia::stat()</code>,
1511	respectively. In particular it affects the amount of printout
1512	at the various stages of operation. See
1513	<a href="MainProgramSettings.html" target="page">here</a> for further details.
1514	This change involves several code changes, but in documentation
1515	rather than physics. Most of the <code>Main:...</code> settings
1516	are deprecated as a consequence.</li>
1517
1518	<li>The sample main programs in the <code>examples</code> subdirectory
1519	have been updated. This includes a change to the new favoured
1520	methods and settings outlined above, plus some update of the
1521	physics contents. Some of the examples have been combined,
1522	some others have been added (e.g. for R-hadroms), and as a consequence
1523	some renumbering has been made. See the modified list of
1524	<a href="SampleMainPrograms.html" target="page">sample main programs</a> for
1525	the new status. In particular note that (the new) <code>main61.cc</code>
1526	allows streamlined input and output in HepMC, like <code>main42.cc</code>
1527	(previously <code>main32.cc</code>), but additionally links to LHAPDF. </li>
1528
1529	<li>The <code>examples/configure</code> script has new optional argument
1530	<code>--with-pythia8</code>. It can be used to set the new
1531	<code>PYTHIA8LOCATION</code> environment variable, which then is used
1532	in <code>examples/Makefile</code> to give the path to the PYTHIA
1533	library. Thereby it becomes possible to relocate (parts of) the
1534	<code>examples</code> directory and still obtain the correct path.
1535	Thanks to Mikhail Kirsanov.</li>
1536
1537	<li>Polarization information has been included as a new
1538	<code>Particle</code> property, that can be set by
1539	<code>void pol(double polIn)</code> and obtained by
1540	<code>double pol()</code>. Default value is <code>9.</code>,
1541	in agreement with the Les Houches standard. Event listings have
1542	been expanded to optionally display this information. Currently
1543	polarization is not used internally.</li>
1544
1545	<li>The matrix element merging machinery has been modified as follows.
1546	<br/>- Improved handling of the hard process, so that MadGraph5-produced
1547	LHE files do not produce problems (sometimes, the choices of MG4 on what
1548	to put into a LHEF have changed in MG5).
1549	<br/>- Improved handling of colour for easier handling of states with
1550	many quarks (the code has been tested for states with up to 5
1551	<i>q qbar</i> pairs and some gluons).
1552	<br/>- Improved checking which clusterings are allowed. Now, clusterings
1553	should immediately be rejected if they lead to unphysical states,
1554	without the need to explicitly construct these states. This was needed
1555	to get <i>t tbar</i> production, VBF and some simple SUSY processes
1556	running with reasonable generality.
1557	<br/>- Improved handling of incomplete histories. Now there is an
1558	additional switch allowing code to try to swap some colours when fewer
1559	clusterings than requested have been found.
1560	</li>
1561
1562	<li>Updates in the handling of graviton resonances in scenarios with
1563	extra dimensions.
1564	<br/>- Now all G decays have correct angular distribution, which was not
1565	the case before for W/Z decays.
1566	<br/>- Added the possibility for G to only couple to longitudinal
1567	W/Z bosons, which affects both the width and angular distributions.
1568	<br/>- Added decays to Higgs pairs, <i>G -> hh</i>.
1569	</li>
1570
1571	<li>Bug fix in the <code>findJunctions()</code> function in
1572	<code>ProcessLevel.cc</code>. Changes introduced in version
1573	8.145 (to allow for junctions in baryon-number-violating
1574	processes) did not correctly handle the remapping of color
1575	tags that can be applied when adding beam remnants to events with
1576	multiparton interactions. A simpler and more stable algorithm is
1577	now applied for the simplest cases, with the more complex one only
1578	invoked for cases such as BNV, which are normally considered before
1579	remnants are added, hence avoiding this particular problem. Also some
1580	other changes in the handling of junction, including a safeguard to
1581	reject systems with three or more interconnected junctions.</li>
1582
1583	<li>Bug fix and updates to the SLHA interface. Possibility of infinite
1584	loop during <code>ProcessLevel::initSLHA</code> corrected. Modifications
1585	to <code>SusyLesHouches</code> to allow interpretation of SLHA1 spectra
1586	with R-parity violation. Rather than reject spectra that do not conform
1587	fully to the SLHA2 standard for RPV, the interface will now first look
1588	for SLHA1 mixing matrices and attempt to translate those into SLHA2 ones
1589	if possible. In this case, warnings that the expected SLHA2 blocks were
1590	not found will be printed. It is up to the user to check that the
1591	derived SLHA2 information is correct. Corresponding additions to
1592	<code>SusyCouplings.cc</code> to extract mixing-matrix information
1593	from the relevant SLHA2 RPV blocks when RPV is switched on.</li>
1594
1595	<li>Updated SLHA example <code>main24.cmnd</code> to use new example
1596	spectrum, <code>cmssm.spc</code>, corresponding to CMSSM point
1597	10.1.1, obtained with SOFTSUSY 3.3.0. Thanks to B. Allanach for
1598	providing the new spectrum file.</li>
1599
1600	<li>A new <code>include/FastJet3.h</code> header file simplifies
1601	interfacing of FastJet to Pythia. For details see documentation in
1602	the file itself. Thanks to Gavin Salam for this contribution.</li>
1603
1604	<li>The handling of diffraction has been made more flexible.
1605	Specifically the "total" Pomeron-proton cross section can now be made
1606	to depend on the mass of the diffractive system. This does not affect
1607	the diffractive cross section in pp collisions, which is set separately,
1608	but is used in the MPI machinery to affect the average number of
1609	interactions per Pomeron-proton collision. Furthermore, the allowed
1610	range for some parameters has been expanded. Thanks to Robert
1611	Ciesielski.</li>
1612
1613	<li>New method <code>Pythia::forceTimeShower(...)</code> can be used to
1614	generate a single final-state cascade from a set of partons, without
1615	any knowledge of prior history. This is mainly intended for toy studies.
1616	The meaning of the <code>ProcessLevel:all</code> switch has been modified
1617	so that this parton-level function is available, but not any others
1618	at this level.
1619	</li>
1620
1621	<li>ATLAS tune A2 now included. Thanks to Deepak Kar for
1622	providing it.</li>
1623
1624	<li>Change in the handling of recoils of timelike showers in resonance
1625	decays, in cases of coloured resonances such as <i>t -> b W</i>. In
1626	the first step the <i>W</i> always acts as recoiler to the <i>b</i>,
1627	but in subsequent step previously the <i>W</i> remained as recoiler to
1628	one dipole, while now all QCD-radiating partons recoil against another
1629	coloured parton. The old behaviour could give a (small) unphysical spike
1630	of radition collinear with the colourless recoiler in the subsequent
1631	emissions (while the pattern of the first was and remains correct).
1632	The old behaviour can be recovered for checks, see
1633	<code>TimeShower:recoilToColoured</code>.
1634	Thanks to Yevgeny Kats for pointing out this issue (previously noted
1635	for Pythia 6 by several persons).
1636	</li>
1637
1638	<li>Bug fixes for <code>rootexamples/Makefile</code> and restoration
1639	of some deleted information in <code>rootexamples/README</code>.
1640	Thanks to Axel Naumann and Bernhard Meirose.</li>
1641
1642	<li>Bug fix, so that displaced vertices are possible in resonance
1643	decay chains. Thanks to Daniel Blackburn and Andy Buckley for
1644	pointing this out.</li>
1645
1646	<li>Bug fix for <code>Info</code> counter 2.</li>
1647
1648	<li>Bug fix so that sextet quarks now are read in correctly from
1649	Les Houches Event files; previously the (anti)colours were set
1650	to 0.</li>
1651
1652	<li>Year updated to 2012 in copyright statements etc.</li>
1653
1654	<li>Reformatting to reduce the number of code lines with more
1655	than 79 characters.</li>
1656
1657	<li><code>Pythia::initSLHA()</code> moved from <code>public</code>
1658	to <code>private</code>.
1659	</li>
1660
1661	<li>Remove warning message when tau polarization is set by hand.</li>
1662
1663	<li>Several minor changes to reduce the number of warnings issued
1664	by the clang compiler. The origin of some warnings remains unclear
1665	so those remain to track down (could also be compiler bugs; note that
1666	we discuss warnings, not errors). Thanks to Randy MacLeod for bringing
1667	this up.</li>
1668
1669	<li>The worksheet has been updated to be in step with Pythia 8.160.</li>
1670
1671	<li>Several other minor corrections in the code and documentation.</li>
1672
1673	</ul>
1674	</li>
1675
1676	<li>8.162: 12 March 2012
1677	<ul>
1678
1679	<li>A new option allows for several partons to share the recoil in
1680	final-state radiation, see<a href="TimelikeShowers.html" target="page">Timelike
1681	Showers</a>. It is mainly intended to be used in the context of
1682	matching to matrix elements, and so only to be used in the first
1683	few branchings.</li>
1684
1685	<li>Several new processes for LED dijet production, see
1686	<a href="ExtraDimensionalProcesses.html" target="page">Extra Dimensions</a>.</li>
1687
1688	<li>Small update of the <code>Sigma2ffbar2LEDllbar</code> and
1689	<code>Sigma2ffbar2LEDgammagamma</code> LED processes.</li>
1690
1691	<li>New <code>Sigma2QCffbar2llbar</code>
1692	<a href="CompositenessProcesses.html" target="page">contact interaction</a>
1693	process.</li>
1694
1695	<li>Inclusion of a new method in the
1696	<a href="MatrixElementMerging.html" target="page">matrix-element merging</a>
1697	framework to influence the construction of histories, e.g. to already
1698	in the construction of histories disallow paths that fail the
1699	<i>2 -> 2</i> cuts.</li>
1700
1701	<li>Further minor updates of the matrix-element merging code,
1702	mainly for improved clarity.</li>
1703
1704	<li>Minor bug fix in the handling of beam and event information fed
1705	in from an <code>LHAup</code> instance.</li>
1706
1707	<li>Minor bug fix for potential crashes from uninitialized variables
1708	for the merging machinery when merging is not used.</li>
1709
1710	<li>Updated History class for matrix element merging,
1711	also avoiding some compiler warnings.</li>
1712
1713	<li>Bug fixes in the handling of correlated mass choices in resonance
1714	decays, such as <i>H -> Z^0 Z^0</i>.</li>
1715
1716	<li>Bug fix when the process-level execution is switched off,
1717	where <code>Info::isResolved()</code> could be called before its
1718	value was initialized. Thanks to Christian Pulvermacher
1719	for finding this.</li>
1720
1721	<li>Corrected matrix-element expression for mass selection in
1722	<i>A^0 -> Z^0 Z^0</i> and <i>A^0 -> W^+ W^-</i>.</li>
1723
1724	<li>SM Higgs mass updated to 125 GeV and default width and branching
1725	ratios modified accordingly. Minor technical improvements of width
1726	calculation.</li>
1727
1728	<li>The usage of nested classes has been removed from
1729	<code>SusyLesHouches</code>, since it could give compilation errors
1730	on some platforms. The new class names begin with <code>LH</code>
1731	and all classes have been put inside the <code>Pythia8</code>
1732	namespace.</li>
1733
1734	<li>Minor Makefile updates. Thanks to Mikhail Kirsanov.</li>
1735
1736	<li>Minor changes to avoid some clang compiler warnings on the
1737	Mac OS X platform.</li>
1738
1739	</ul>
1740	</li>
1741
1742	<li>8.163: 27 March 2012
1743	<ul>
1744
1745	<li>New methods in the
1746	<a href="EventInformation.html" target="page"><code>Info</code></a> class,
1747	<code>id1pdf()</code>, <code>id2pdf()</code>, <code>x1pdf()</code>
1748	and <code>x2pdf()</code>, to denote the partons for which parton
1749	distribution values have been defined. Previously this was assumed
1750	to agree with the incoming partons to the hard process, the same
1751	methods without the <code>pdf</code> qualifier. However, now the
1752	POWHEG approach offers a counterexample. Also the reading and
1753	handling of Les Houches (and other) events, and the interface
1754	to HepMC, has been modified accordingly.
1755	</li>
1756
1757	<li>The decay of Higgs and top resonances read in from Les Houches
1758	Event files is now performed with angular correlations as for
1759	internal processes. LHE files should normally contain all process-specific
1760	resonance decay chains and, if not, decays are made isotropic.
1761	The <i>H -> WW/ZZ -> f fbar f' fbar'</i> and
1762	<i>t -> b W -> b f fbar</i> correlations are process-independent,
1763	however, and thus can be handled internally. If part of the decay
1764	chain has already been set, e.g. <i>H -> WW/Z></i> or <i>t -> b W</i>,
1765	then the subsequent decays are still isotropic.</li>
1766
1767	<li>Updated instructions how to link to HepMC,
1768	in <code>README.HepMC</code>.</li>
1769
1770	<li>Bug fix in the turn-on of resolved diffraction for low
1771	CM energies. Thanks to Erwin Visser.</li>
1772
1773	<li>Bug fix in the handling of string junctions at very high energies,
1774	caused by numerical errors. Thanks to Erwin Visser.</li>
1775
1776	<li>Some other small changes, mainly aesthetics.</li>
1777
1778	</ul>
1779	</li>
1780
1781	<li>8.165: 8 May 2012
1782	<ul>
1783
1784	<li>The MBR (Minimum Bias Rockefeller) model for single, double and
1785	central diffraction [<a href="Bibliography.html" target="page">Cie12</a>] is included as new option
1786	<a href="Diffraction.html" target="page"><code>Diffraction:PomFlux = 5</code></a>.
1787	It is specifically intended for <i>p p</i> and <i>pbar p</i>
1788	interactions, and is currently the only option that also supports
1789	central diffraction. Thus the basic machinery for Central Diffraction
1790	(a.k.a. Double Pomeron Exchange) has now been implemented.
1791	See <code>examples/main04.cc</code> for an example.
1792	Thanks to Robert Ciesielski for contributing the new code.
1793	</li>
1794
1795	<li>For a <i>tau</i> lepton in an external process, by default the
1796	SPINUP number in the Les Houches Accord now is interpreted as giving
1797	the <i>tau</i> helicity, and is used for its decay.</li>
1798
1799	<li>A <i>tau</i> coming from a <i>W</i> now defaults to being purely
1800	lefthanded when neither of the existing matrix elements apply.</li>
1801
1802	<li>Decay mode <i>t -> H+ b</i> included as an option.</li>
1803
1804	<li>Four ATLAS tunes have been implemented as options for
1805	<code>Tune:pp</code>: A2-minbias-mstw2008lo, AU2-cteq6l1, AU2-mstw2008lo,
1806	and AU2-ct10. The new flag <code>Tune:preferLHAPDF</code> can be used
1807	to switch between the LHAPDF and the internal implementation of a
1808	PDF set, in cases where both are available.</li>
1809
1810	<li>Reorder libraries in <code>examples/Makefile</code>, specifically
1811	move <code>LIBGZIP</code> so that it is properly linked when used.
1812	Thanks to Erik Schnetter.</li>
1813
1814	<li>Minor modification so that LHAPDF can be used for PDFs in the hard
1815	process, with one of the built-in PDFs for the rest, even if LHAPDF is
1816	compiled so as to handle only one concurrent PDF set.</Li>
1817
1818	<li>Bug fix, that <code>ParticleDecays:mixB = off</code> did not
1819	switch off <i>B0 - B0bar</i> and <i>Bs0 - Bs0bar</i> mixing.
1820	Thanks to James Catmore.</li>
1821
1822	<li>Bug fix for the handling of gluon polarization of initial-state
1823	radiation, where an anisotropic azimuthal distribution was inadvertently
1824	generated in some <i>2 -> 1</i> processes. The update also includes
1825	always setting the second daughter zero for the two partons coming in to
1826	a hard <i>2 -> 1</i> process. Thanks to Antonio Policicchio.</li>
1827
1828	<li>Bug fix, that the setting of the number of user hooks MPI steps did
1829	not use <code>UserHooks::canVetoMPIStep()</code> properly.</li>
1830
1831	<li>Some other small changes, mainly documentation and aesthetics.</li>
1832
1833	</ul>
1834	</li>
1835
1836	<li>8.170: 21 September 2012
1837	<ul>
1838
1839	<li>Streamline default behaviour and options for choice of GeV or MeV
1840	for output to the HepMC event format, see
1841	<a href="HepMCInterface.html" target="page">HepMC Interface</a>.
1842	Also set the mass of HepMC particles explicitly, rather than having
1843	it calculated implicitly. Thanks to James Monk and Andy Buckley.</li>
1844
1845	<li>The <i>tau</i> decay machinery has been further augmented with
1846	matrix elements and form factors for a variety of decay modes, such
1847	that all modes with a branching ratio above 0.1% are fully modelled.
1848	Several new classes and methods have been added to this end,
1849	Also, a <i>tau</i> pair coming from a <i>Z^0</i> decay is now
1850	handled by assuming the <i>Z^0</i> to be unpolarized when neither
1851	of the existing matrix elements apply. Taus coming from B baryons are
1852	handed as for B mesons.</li>
1853
1854	<li>Flavour violating decays have been added to the squark, gluino,
1855	neutralino and chargino decay tables.</li>
1856
1857	<li>Extend the <code>UserHooks::subEvent(...)</code> method so that it
1858	also works passably at the process level. Also new option for
1859	<code>UserHooks::omitResonanceDecays(...)</code>.</li>
1860
1861	<li>New methods <code>UserHooks::canVetoPartonLevelEarly()</code>
1862	and <code>UserHooks::doVetoPartonLevelEarly( const Event&)</code>
1863	are intended to be used the same way as the existing ones without
1864	<code>Early</code> in their names, but allow veto right after
1865	the ISR + FSR + MPI evolution, before beam remnants are added and
1866	resonance decays are considered.</li>
1867
1868	<li>Central diffraction now available for all
1869	<code><a href="Diffraction.html" target="page">PomFlux</a></code>
1870	options, not only the MBR model. This has been constructed by analogy
1871	with the respective assumptions made for single diffraction, but
1872	includes some arbitrariness. Therefore the cross section is left
1873	easily rescaleable and, for backwards compatibility with tunes
1874	that does not contain it, easily possible to switch off, see
1875	the <a href="TotalCrossSections.html" target="page">relevant section</a>.
1876	</li>
1877
1878	<li>Reading of ALPGEN parameter and event files has been added,
1879	see <a href="AlpgenAndMLM.html" target="page">ALPGEN and MLM Merging</a>.
1880	</li>
1881
1882	<li>MLM matching has been added, as a first step for ALPGEN events,
1883	see <a href="AlpgenAndMLM.html" target="page">ALPGEN and MLM Merging</a>.
1884	</li>
1885
1886	<li>The CKKW-L merging machinery has been upgraded in a number of respects.
1887	<br/>- More thorough treatment of <code>pp>bb~e+e-veve~</code> with
1888	additional <i>b</i>-jets.
1889	<br/>- Corrected hard <i>mu_r</i> and <i>mu_f</i> choices for
1890	dijet and promt photon.
1891	<br/>- More ways to define a hard process, e.g. with the LEPTONS and
1892	NEUTRINO tags. The merging will understand LHE files for mixed processes
1893	(e.g. <i>W+</i> and <i>W-</i> production together).
1894	<br/>- More merging scale definitions.
1895	<br/>- More freedom to generate all possible histories.
1896	<br/>- Internal check (and cut) on Les Houches events in
1897	<code>Pythia::mergeProcess</code> if merging scale value of the events
1898	is below the value given to Pythia by setting <code>Merging::TMS</code>.
1899	</li>
1900
1901	<li>It now works to have R-parity violating decays of R-hadrons,
1902	i.e. baryon number violation in a vertex displaced from the primary
1903	one.</li>
1904
1905	<li>The documentation of diffractive processes by the
1906	<code><a href="EventInformation.html" target="page">Info</a></code>
1907	methods has been expanded and corrected. This also include the
1908	<code>list()</code> method.</li>
1909
1910	<li>Particle masses and widths have been updated to agree with the
1911	2012 RPP values [<a href="Bibliography.html" target="page">Ber12</a>]. Thanks to Piotr Zyla for data file
1912	and James Catmore for program to update the PYTHIA tables from this
1913	input.</li>
1914
1915	<li>New methods <code>jetAssignment</code> and <code>removeJet</code>
1916	added to the <code>SlowJet</code> class.</li>
1917
1918	<li>Introduce angular correlation in decay chain
1919	<i>H -> gamma Z0 -> gamma f fbar</i>. Thanks to Tim Barklow and
1920	Michael Peskin.</li>
1921
1922	<li>Introduce simple way to bias the selection of <i>2 -> 2</i>
1923	processes towards larger <i>pT</i> values, with a compensatingly
1924	decreasing event weight, see
1925	<a href="PhaseSpaceCuts.html" target="page">Phase Space Cuts</a>. Only offers a
1926	subset of the possibilities allowed by <code>UserHooks</code>,
1927	but simpler to use. The <code>main08.cc</code> program has been
1928	expanded to illustrate this possibility, and also expanded to
1929	include low-<i>pT</i> subsamples.</li>
1930
1931	<li>The two remaining non-NLO tunes from [<a href="Bibliography.html" target="page">ATL12</a>] are now
1932	included.</li>
1933
1934	<li>The <code><a href="EventInformation.html" target="page">Info</a></code> methods
1935	<code>nTried, nSelected, nAccepted, sigmaGen</code> and
1936	<code>SigmaErr</code> now takes the code of an individual process
1937	as an optional argument.</li>
1938
1939	<li>It is now possible to generate resonance decays, followed by
1940	showers and hadronization, without having them associated with any
1941	specific process. This is part of an expanded
1942	<a href="HadronLevelStandalone.html" target="page">Hadron-Level Standalone</a>
1943	machinery, as before triggered by <code>ProcessLevel = off</code>,
1944	but additionally requiring <code>Standalone:allowResDec = on</code>.
1945	Input can either be directly into the <code>event</code>
1946	event record or via a (simplified) Les Houches Event File.</li>
1947
1948	<li>New <code>configure</code> script options <code>--installdir</code>,
1949	<code>--prefix</code> and <code>--datadir</code> can be used to set the
1950	location(s) to which the library, header and data directories
1951	will be copied by a <code>make install</code> subsequent to the
1952	<code>make</code>. Thanks to Mikhail Kirsanov.</li>
1953
1954	<li>Fix charge in antiparticle name when particle read in from SLHA
1955	file. Thanks to Johan Alwall.</li>
1956
1957	<li>Pointers now only compared with == and != (not e.g. > 0), to avoid
1958	warnings in gcc 4.7.</li>
1959
1960	<li>New check that version number of the code matches that of the
1961	XML files. If not, no events can be generated. Thanks to James Monk
1962	for suggestion.</li>
1963
1964	<li>New check that mother and daughter indices have been set to give
1965	a consistent event history. Can be switched on/off with the new
1966	<code>Check:history</code> flag.</li>
1967
1968	<li>A new method <code>LHAup::newEventFile</code> has been added to
1969	switch to reading in events from another LHE file without having to
1970	reinitialize the whole class. Lower-level routines like
1971	<code>openFile</code> and <code>closeFile</code> have been added to
1972	handle correct order of operations also when an intermediate gzip
1973	decompression step is involved.</li>
1974
1975	<li><code>LHAup::eventLHEF()</code> can now be called with an optional
1976	argument <code>false</code>, to make event files somewhat smaller by
1977	reducing the amount of blanks.</li>
1978
1979	<li>A new mode <code>Beams:nSkipLHEFatInit</code> introduced to
1980	skip ahead the first few events in a Les Houches Event File (cf. the
1981	<code>LHAup::skipEvent(nSkip)</code> method).</li>
1982
1983	<li>Introduce a new pair of user hooks that can be used to reject
1984	the sequence of hard-process resonance decays, without rejecting
1985	the production of the primary resonances.</li>
1986
1987	<li>The possibility of separate multiplicative prefactors to the
1988	renormalization and factorization default <i>pT^2</i> scale has been
1989	introduced for both timelike and spacelike showers.</li>
1990
1991	<li>Bug fixes in history information for R-hadron production, which also
1992	fixes HepMC conversion in this case.</li>
1993
1994	<li>Bug corrected in <code>SigmaSusy.cc</code>, for chargino+neutralino
1995	production. Indexing error for incoming quark states in the process
1996	<code>Sigma2qqbar2charchi0</code>, resulted in incorrect CKM factors.</li>
1997
1998	<li>Corrected a bug in <code>SusyLesHouches.cc</code>, for NMSSM spectra.
1999	The unitarity check on the neutralino mixing matrix was faulty, leading
2000	to erroneous messages about unitarity violations and SUSY being switched
2001	off.</li>
2002
2003	<li>Bug fixes in the handling of resolved and unresolved diffractive events.
2004	Thanks to Robert Ciesielski for debug.</li>
2005
2006	<li>Do not set up FSR dipoles for <i>2 -> 1</i> processes.</li>
2007
2008	<li>Check that some channel open for resonance decays. Also further
2009	check whether resonance decay treatment should be invoked.</li>
2010
2011	<li>Bug fix in reading of particle names from SLHA input.</li>
2012
2013	<li>Change mass, width and decay mode(s) of D*_s(10431). Thanks to
2014	Michal Petran.</li>
2015
2016	<li>Bug fix in leptoquark production (lepton sign in
2017	<i>q g -> LQ l</i>).</li>
2018
2019	<li>New argument added to <code>SpaceShower::reassignBeamPtrs</code>
2020	for diffractive event processing, as already available for
2021	<code>TimeShower</code>.</li>
2022
2023	<li>Do not write warnings in <code>SpaceShower</code> for weights
2024	above unity if the evolution scale is below 1 GeV^2.</li>
2025
2026	<li>Add default values for member variables in some constructors,
2027	and some related changes for <code>AlphaStrong</code> code.</li>
2028
2029	<li>Warn if negative-energy parton in hadronization.</li>
2030
2031	<li>The MPI <i>pT</i> values assumed in the beam remnant setting
2032	of primordial <i>kT</i> and colour reconnection probability were
2033	incorrect for diffractive events.</li>
2034
2035	<li>The arrays with MPI information were not reset when parton or
2036	hadron level fails and a new try is made. Only affected few events.</li>
2037
2038	<li>MPI statistics can not yet be accumulated for diffractive events,
2039	and therefore the relevant routine is no longer called.</li>
2040
2041	<li>Bug fix in the double parton scattering suppression from
2042	energy-momentum conservation.</li>
2043
2044	<li>Outgoing proton masses were not set in the event record for
2045	elastic scattering (but kinematics handling was correct).</li>
2046
2047	<li>Bug fixes in the identification and documentation of junctions,
2048	previously leading to some unnecessarily rejected events. Also
2049	other improvements leading to fewer errors.</li>
2050
2051	<li>Slightly increased values for FragmentationSystems:mJoin and
2052	StringFragmentation::FACSTOPMASS to reduce failure rate, without
2053	noticeably affecting event properties.</li>
2054
2055	<li>The Les Houches cross section error is now taken into account
2056	in the final Pythia error for strategies +-3. New methods
2057	<code>LHAup::xSecSum()</code> and <code>LHAup::xErrSum()</code>
2058	provide the necessary information.
2059	</li>
2060
2061	<li>When a tau pair comes from a massless photon, in dipole shower
2062	evolution, for the decay description the mother photon is reassigned
2063	to have the sum of the tau momenta.</li>
2064
2065	<li>Minor change in initialization sequence for user hooks,
2066	to allow for more flexibility.</li>
2067
2068	<li>Do not print warnings when multiparton interaction weights are
2069	only slightly above unity.</li>
2070
2071	<li>Do not write warnings for three known particles that are so close
2072	to threshold that widths are switched off to avoid trouble.</li>
2073
2074	<li>Some minor typographical changes.</li>
2075
2076	</ul>
2077	</li>
2078	</ul>
2079
2080	</body>
2081	</html>
2082
2083	<!-- Copyright (C) 2012 Torbjorn Sjostrand -->

Note: See TracBrowser for help on using the repository browser.

Context Navigation

source: HiSusy/trunk/Pythia8/pythia8170/htmldoc/UpdateHistory.html @ 1

Download in other formats: