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Click here for the FastPrune plugin to FastJet, implementing jet pruning. The rest of this webpage is somewhat out of date...

This page contains software and documentation for jet pruning, as described in this short paper and this long paper.

UW held a workshop in January to discuss jet substructure methods, including pruning. A lot of interesting information is available at the workshop wiki.

Some recent talks that discuss pruning:

Jon Walsh, "Jet Substructure Tools for the LHC", + PowerPoint version, seminar talk given to UW experimental group, Fall 2009
Jon Walsh, "Understanding and Using Jet Substructure at the LHC", + PowerPoint version, seminar talk given Fall 2009 (SLAC, Johns Hopkins, Maryland, MIT, Harvard, Berkeley). See below for animations.
Steve Ellis, "Jet Pruning: Looking for New (BSM) Physis at the LHC with Single Jets", BOOST workshop @ SLAC, 7/9/09.
Steve Ellis, "Jet Pruning: Looking for New (BSM) Physis at the LHC with Jets", Fermilab, 5/18/09.
Jon Walsh, "Jet Pruning: A Study on Top Quarks", Fermilab, 5/18/09.
Chris Vermilion, "Jet Pruning: A User's Guide", Fermilab, 5/18/09.

Software:

FastJet is widely used software that can run various jet algorithms. We have implemented a pruning plug-in for FastJet that is currently being developed and improved. You can find it here.

Note: the plugin is in beta release -- please email us if you find bugs or would like to request additional featues.

In studying various substructure methods, we have found the SpartyJet package useful. Information on using SpartyJet with FastJet plugins is available at the workshop wiki linked above.

Animations:

We have made Mathematica-based visualizations of the recombination process in the kT and Cambridge-Aachen (CA) jet algorithms. These show, for individual jets, how cells are recombined in a step-by-step animation. The animations also implement pruning, showing how it operates on jets.

Notes on the animations: they show 0.05-by-0.05 cells recombined in rapidity-phi space. A cut selects cells with energy > 1 GeV, and the color of the cell is related to the pT. At each stage in the animation, the highest pT cell is red, and the color smoothly interpolates to blue as the pT decreases towards zero. The code for the animations also produces animations in z-Delta R space, which also serves a nice illustration of which regions are pruned for each algorithm.

(Right-click to download files)

The code

data for 100 heavy QCD jets, CA

data for 100 heavy QCD jets, kT

data for 100 top jets, CA

data for 100 top jets, kT

Sample animation of a heavy QCD jet with CA

Sample animation of a heavy QCD jet with pruned CA

Sample animation of a heavy QCD jet with kT

Sample animation of a heavy QCD jet with pruned kT

Sample animation of a heavy top jet with CA

Sample animation of a heavy top jet with pruned CA

Sample animation of a heavy top jet with kT

Sample animation of a heavy top jet with pruned kT

Sample dR vs. z animation for a heavy QCD jet with pruned CA (same jet as above pruned CA animation)

Sample dR vs. z animation for a heavy QCD jet with pruned KT (same jet as above pruned KT animation)

For questions or support, contact:
Chris Vermilion ([last four letters of my last name]@uw.edu)
Jon Walsh (['jr' + his last name]@uw.edu)