Jet algorithms in cut/analysis

[kilian]

The cut/analysis expression language should have the possibility of defining parton collections by a jet algorithm.

Think of an interface to FastJet? and friends.

[Juergen Reuter]

One of the standard references is Run II Jet Physics, hep-ex/0005012.

[ohl]

• ​http://www.lpthe.jussieu.fr/~salam/fastjet/
• ​http://arxiv.org/abs/hep-ex/0005012

[ohl]

• ​http://www.lpthe.jussieu.fr/~salam/fastjet/
• ​http://arxiv.org/abs/hep-ex/0005012
• ​http://arxiv.org/abs/0802.1189

[Juergen Reuter]

After phone call with WK: this is along the same lines as #430 and will/should be dealt with on the same time scale.

[Juergen Reuter]

As discussed today: if there is a 2.0.8 it will be more an ILC/CLIC-related release.

[kilian]

Was actually straightforward, done in r5843.

Documented in the manual, essentially there are three items:

1. function cluster, quite similar to the more trivial collect
2. integer variable jet_algorithm with predefined constants as possible values
3. real variable jet_r

Discussion welcome. Possible enhancements:

• include the lightweight fjet.cc file as fallback
• the C++ interface works but is a bit clumsy, some C++ guru might be able to simplify it
• access more functionality than just inclusive jets
• use cases?

[Bijan Chokoufe Nejad]

Internal clustering analogue to FastJet has been implemented and will most likely be added in a small library in the context of #499 such that it can used in shower as well as whizard.

[Juergen Reuter]

We should test once that distributions with internal FastJet? clustering and analysis are identical to those done with Rivet.