hephysics.jet

Class JetN2

java.lang.Object

hephysics.jet.JetN2

public class JetN2
extends Object

JetN2 is an implementation of the longitudinally-invariant kT, anti-KT and Cambridge/Aachen clustering algorithms. The algorithm uses rapidity-phi for the distance parameter and double values for merging. The input and output for this algorithm is ParticleD class.

This class uses double values for calculations, caching and requires more memory, compared to the light-weight KTjet class that uses floats and pseudo-rapidity to define the distance parameter. This implementation can access jet constituents.

This algorithm is similar to the N2 FastJet http://fastjet.fr/ implementation that uses rapidity. The method uses E-scheme to combine particles (p1+p2). More details is in http://arxiv.org/pdf/hep-ph/0210022v1.pdf.

Constructor Summary

Constructors

Constructor and Description
JetN2(double R) Initialize calculations of the kT algorithm.
JetN2(double R, double minpt) Initialize calculations of the antikT algorithm.
JetN2(double R, int recom, String type, double minpt) Initialize calculations of the longitudinally invariant kT algorithm in inclusive mode.
JetN2(double R, String type, double minpt) Initialize calculations of the longitudinally invariant kT algorithm in inclusive mode.

Method Summary

Modifier and Type	Method and Description
List<ParticleD>	buildJets(List<ParticleD> list) Run the jet algorithm using the list of particles.
ArrayList<ParticleD>	getJetsSorted() Get jets after sorting in jet pT.
String	info() Return information about the jet setting.
static void	main(String[] args) Main class for testing.
void	printJets() Print the kT jets for debugging.
void	setDebug(boolean debug) Print debugging information.
String	toString() Print the kT jets for debugging to a string.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

JetN2

public JetN2(double R,
             int recom,
             String type,
             double minpt)

Initialize calculations of the longitudinally invariant kT algorithm in inclusive mode. Jet can be clustered using Cambridge/Aachen or anti-kT approaches, depending on the "mode" parameter. The distance parameters are rapidity and phi.

Parameters:

R - distance measure

recom - recombination scheme.
1: The E-scheme Simple 4-vector addition.
2: The pT-scheme (not implemented)
3: The pT^2 scheme (not implemented)
Currently only E-scheme is implemented.

type - [kt,antikt,ca]
clustering mode dij=min(kT_i^{2* mode},kT_j^{2* mode})).
kt : means inclusive kT jet algorithm
ca: means Cambridge/Aachen jet algorithm
antikt: means anti-KT jet algorithm

minpt - min pT for final jets.

JetN2

public JetN2(double R,
             String type,
             double minpt)

Initialize calculations of the longitudinally invariant kT algorithm in inclusive mode. Jet can be clustered using Cambridge/Aachen or anti-kT approaches, depending on the "type" parameter. The distance parameters are rapidity and phi. The E-scheme with 4-vector addition is used.

Parameters:

R - distance measure

type - [kt,antikt,ca]
clustering mode dij=min(kT_i^{2* mode},kT_j^{2* mode})).
kt : means inclusive kT jet algorithm
ca: means Cambridge/Aachen jet algorithm
antikt: means anti-KT jet algorithm

minpt - min pT for final jets.

JetN2

public JetN2(double R,
             double minpt)

Initialize calculations of the antikT algorithm. Meaningful values are R=0.2- 1. Jets are clustered in rapidity and phi space. The E-scheme with 4-vector addition is used.

Parameters:

R - distance measure

minpt - min pT for final jets.

JetN2

public JetN2(double R)

Initialize calculations of the kT algorithm. Meaningful values are R=0.2- 1. Jets are clustered in rapidity and phi space. The E-scheme with 4-vector addition is used. Minumum pT is set to 5 GeV.

Parameters:

R - distance measure

Method Detail

buildJets

public List<ParticleD> buildJets(List<ParticleD> list)

Run the jet algorithm using the list of particles.

Parameters:

list - list with particles

Returns:

final jets without sorting.

getJetsSorted

public ArrayList<ParticleD> getJetsSorted()

Get jets after sorting in jet pT. Run buildJets before calling this method.

Returns:

list with sorted jets

printJets

public void printJets()

Print the kT jets for debugging.

toString

public String toString()

Print the kT jets for debugging to a string.

Overrides:

toString in class Object

Returns:

String representing a jet

setDebug

public void setDebug(boolean debug)

Print debugging information. It shows how much time spend to make jets in ms.

Parameters:

debug - true if printing benchmark information.

info

public String info()

Return information about the jet setting.

Parameters:

info - Information on the current settings.

main

public static void main(String[] args)

Main class for testing.

Parameters:

args -