fastjet::RestFrameNSubjettinessTagger Class Reference

Class that helps perform 2-pronged boosted tagging using a reclustering in the jet's rest frame, supplemented with a cut on N-subjettiness (and a decay angle), as discussed by Ji-Hun Kim in arXiv:1011.1493. More...

#include <fastjet/tools/RestFrameNSubjettinessTagger.hh>

Inheritance diagram for fastjet::RestFrameNSubjettinessTagger:

Collaboration diagram for fastjet::RestFrameNSubjettinessTagger:

List of all members.

Public Types
typedef RestFrameNSubjettinessTaggerStructure	StructureType
	the type of Structure returned
Public Member Functions
	RestFrameNSubjettinessTagger (const JetDefinition subjet_def, const double tau2cut=0.08, const double costhetascut=0.8, const bool use_exclusive=false)
	ctor with arguments (see the class description above)
virtual std::string	description () const
	returns a textual description of the tagger
virtual PseudoJet	result (const PseudoJet &jet) const
	runs the tagger on the given jet and returns the tagged PseudoJet if successful, a PseudoJet==0 otherwise (standard access is through operator()).
Protected Attributes
JetDefinition	_subjet_def
double	_t2cut
double	_costscut
bool	_use_exclusive

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Detailed Description

Class that helps perform 2-pronged boosted tagging using a reclustering in the jet's rest frame, supplemented with a cut on N-subjettiness (and a decay angle), as discussed by Ji-Hun Kim in arXiv:1011.1493.

To tag a fat jet, the tagger proceeds as follows:

• boost its constituents into the rest frame of the jet

• recluster them using another jet definition (the original choice was SISCone in spherical coordinates with R=0.6 and f=0.75.

• keep the 2 most energetic subjets ( ) and compute the 2-subjettiness

  

  where the sum runs over the constituents of the jet.

• require [0.08 by default]

• impose that (in the rest frame of the fat jet), the angles between the 2 most energetic subjets and the boost axis are both large enough: [0.8 by default]

Note that in the original version, the jets to be tagged were reconstructed using SISCone with R=0.8 and f=0.75. Also, b-tagging was imposed on the 2 subjets found in the rest-frame tagging procedure.

Options

The constructor has the following arguments:

• The first argument is the jet definition to be used to recluster the constituents of the jet to be filtered (in the rest frame of the tagged jet).
• The second argument is the cut on tau_2 [0.08 by default]
• The 3rd argument is the cut on cos(theta_s) [0.8 by default]
• If the 4th argument is true, 2 exclusive rest-frame jets will be considered in place of the 2 most energetic inclusive jets

Input conditions

• the original jet must have constituents

Output/structure

• the 2 subjets are kept as pieces if some substructure is found, otherwise a single 0-momentum piece
• the tau2 and maximal cos(theta_s) values computed during the tagging can be obtained via the resulting jet's structure_of<...>() function

Definition at line 99 of file RestFrameNSubjettinessTagger.hh.

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Member Function Documentation

PseudoJet fastjet::RestFrameNSubjettinessTagger::result

(

const PseudoJet &

jet

)

const [virtual]

runs the tagger on the given jet and returns the tagged PseudoJet if successful, a PseudoJet==0 otherwise (standard access is through operator()).

impose the cut on cos(theta_s)

Implements fastjet::Transformer.

Definition at line 57 of file RestFrameNSubjettinessTagger.cc.

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The documentation for this class was generated from the following files:

• tools/fastjet/tools/RestFrameNSubjettinessTagger.hh
• tools/RestFrameNSubjettinessTagger.cc