Pythia comes with three built-in
ClusterJet for e^+e^- events
CellJetfor hadron collider ones.
Especially the latter is not so well matched to the standards of its field,
however. (But it is closely related to the anti-kT algorithm,
so is also not completely disconnected [Cac08].)
SlowJet can do jet finding according to the current-day
kT, Cambridge/Aachen and anti-kT algorithms.
It can be run in two modes. The original one is a native implementation
which, as the name indicates, is rather slow. However, with the release
fjcore code from
[Cac06, Cac12], the default mode has become to use the
fjcore methods. This is transparent to the user.
SlowJet does not exhaust all the posssibilities of the
fjcore code, so users are welcome to extend on the existing
functionality by a direct usage of the
fjcore is a number of aspects, such as
jet areas functionality, background estimation, access to other algorithms
via plugins, interface to CGAL and tools such as filters and taggers.
Therefore, for more sophisticated jet studies the complete
FastJet package needs to be linked. This is foreseen in the
configure file in the
examples subdirectory, and the
main72.cc programs contain
examples how it can be used with
Pythia events. (Even if
these examples do not go beyond the functionality that
SlowJet can offer.)
The latter program makes use of the
header file, contributed by Gavin Salam. This allows simple input
Pythia particle into a
either retaining only the four-momentum or the full particle information.
Thereby more sophisticated selectors become possible at the
FastJet level. This code could be duplicated, with trivial
modifications, to augment the
fjcore package functionality
in an identical manner, should the need arise.