FastJet  3.4.0-beta.1
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fastjet::CASubJetTagger Class Reference

clean (almost parameter-free) tagger searching for the element in the clustering history that maximises a chosen distance More...

#include <fastjet/tools/CASubJetTagger.hh>

Inheritance diagram for fastjet::CASubJetTagger:
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Collaboration diagram for fastjet::CASubJetTagger:
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class  JetAux
 class that contains the result internally More...

Public Types

enum  ScaleChoice {
  kt2_distance, jade_distance, jade2_distance, plain_distance,
  mass_drop_distance, dot_product_distance
 the available choices of auxiliary scale with respect to which to order the splittings
typedef CASubJetTaggerStructure StructureType
 the type of Structure returned
- Public Types inherited from fastjet::Transformer
typedef PseudoJetStructureBase StructureType
 A typedef that is needed to ensure that the PseudoJet::structure_of() template function works.

Public Member Functions

 CASubJetTagger (ScaleChoice scale_choice=jade_distance, double z_threshold=0.1)
 just constructs
void set_dr_min (double drmin)
 sets a minimum delta R below which spliting will be ignored (only relevant if set prior to calling run())
virtual std::string description () const
 returns a textual description of the tagger
void set_absolute_z_cut (bool abs_z_cut=true)
 If (abs_z_cut) is set to false (the default) then for a splitting to be considered, each subjet must satisfy. More...
virtual PseudoJet result (const PseudoJet &jet) const
 runs the tagger on the given jet and returns the tagged PseudoJet if successful, or a PseudoJet==0 otherwise (standard access is through operator()).
- Public Member Functions inherited from fastjet::Transformer
 Transformer ()
 default ctor
virtual ~Transformer ()
 default dtor
- Public Member Functions inherited from fastjet::FunctionOfPseudoJet< PseudoJet >
 FunctionOfPseudoJet ()
 default ctor
virtual ~FunctionOfPseudoJet ()
 default dtor (virtual to allow safe polymorphism)
virtual std::string description () const
 returns a description of the function (an empty string by default)
PseudoJet operator() (const PseudoJet &pj) const
 apply the function using the "traditional" () operator. More...
std::vector< PseudoJetoperator() (const std::vector< PseudoJet > &pjs) const
 apply the function on a vector of PseudoJet, returning a vector of the results. More...

Protected Member Functions

void _recurse_through_jet (const PseudoJet &current_jet, JetAux &aux_max, const PseudoJet &original_jet) const

Protected Attributes

ScaleChoice _scale_choice
double _z_threshold
double _dr2_min
bool _absolute_z_cut

Static Protected Attributes

static LimitedWarning _non_ca_warnings

Detailed Description

clean (almost parameter-free) tagger searching for the element in the clustering history that maximises a chosen distance

class to help us get a clean (almost parameter-free) handle on substructure inside a C/A jet. It follows the logic described in arXiv:0906.0728 (and is inspired by the original Cambridge algorithm paper in its use of separate angular and dimensionful distances), but provides some extra flexibility.

It searches for all splittings that pass a symmetry cut (zcut) and then selects the one with the largest auxiliary scale choice (e.g. jade distance of the splitting, kt distance of the splitting, etc.)

By default, the zcut is calculated from the fraction of the child pt carried by the parent jet. If one calls set_absolute_z_cut the fraction of transverse momentum will be computed wrt the original jet.

original code copyright (C) 2009 by Gavin Salam, released under the GPL.


Input conditions


Definition at line 106 of file CASubJetTagger.hh.

Member Function Documentation

◆ set_absolute_z_cut()

void fastjet::CASubJetTagger::set_absolute_z_cut ( bool  abs_z_cut = true)

If (abs_z_cut) is set to false (the default) then for a splitting to be considered, each subjet must satisfy.

   p_{t,sub} > z_threshold * p_{t,parent}

whereas if it is set to true, then each subject must satisfy

   p_{t,sub} > z_threshold * p_{t,original-jet}

where parent is the immediate parent of the splitting, and original jet is the one supplied to the run() function.

Only relevant is called prior to run().

Definition at line 146 of file CASubJetTagger.hh.

◆ _recurse_through_jet()

void fastjet::CASubJetTagger::_recurse_through_jet ( const PseudoJet jet,
JetAux aux,
const PseudoJet original_jet 
) const

work through the jet, establishing a distance at each branching

make sure the objects are not too close together

Definition at line 105 of file

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