[1] | 1 | <chapter name="Jet Finders"> |
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| 2 | |
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| 3 | <h2>Jet Finders</h2> |
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| 4 | |
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| 5 | <code>Pythia</code> comes with three <aloc href="EventAnalysis">built-in |
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| 6 | jet finders</aloc>, <code>ClusterJet</code> for <ei>e^+e^-</ei> events |
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| 7 | and <code>SlowJet</code> and <code>CellJet</code>for hadron collider ones. |
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| 8 | Especially the latter is not so well matched to the standards of its field, |
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| 9 | however. (But it is closely related to the anti-<ei>kT</ei> algorithm, |
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| 10 | so is also not completely disconnected <ref>Cac08</ref>.) |
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| 11 | <code>SlowJet</code> can do jet finding according to the current-day |
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| 12 | <ei>kT</ei>, Cambridge/Aachen and anti-<ei>kT</ei> algorithms but, |
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| 13 | as the name indicates, is is rather slow, especially when compared with |
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| 14 | the <code>FastJet</code> alternative. |
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| 15 | |
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| 16 | <h3>FastJet</h3> |
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| 17 | |
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| 18 | For realistic jet studies the <code>FastJet</code> package |
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| 19 | <ref>Cac06</ref> has become a standard. Several different |
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| 20 | jet options are available, such as <ei>kT</ei>, |
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| 21 | Cambridge/Aachen, anti-<ei>kT</ei> and SISCone. |
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| 22 | |
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| 23 | <p/> |
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| 24 | Linking to <code>FastJet</code> is foreseen in the configure |
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| 25 | file in the <code>examples</code> subdirectory, and the |
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| 26 | <code>main71.cc</code> and <code>main72.cc</code> programs contain |
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| 27 | examples how it can be used with <code>Pythia</code> events. |
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| 28 | |
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| 29 | <p/> |
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| 30 | The latter program makes use of the <code>include/FastJet3.h</code> |
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| 31 | header file, contributed by Gavin Salam. This allows simple input |
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| 32 | of a <code>Pythia</code> particle into a <code>FastJet</code> one, |
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| 33 | either retaining only the four-momentum or the full particle information. |
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| 34 | Thereby more sophisticated selectors become possible at the |
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| 35 | <code>FastJet</code> level. |
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| 36 | |
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| 37 | </chapter> |
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| 38 | |
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| 39 | <!-- Copyright (C) 2012 Torbjorn Sjostrand --> |
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