hephysics.jet

Class KTjet

java.lang.Object

hephysics.jet.KTjet

public class KTjet
extends Object

Longitudinally-invariant kT, anti-KT and Cambridge/Aachen clustering algorithms (light-weight implementation). This class uses float values for fast computation and ParticleF with float definitions. The algorithm uses phi-pseudorapidity to define distances, similar to the Tevatron approach.

To speed-up calculations and to have a low memory footprint, it uses ParticleF with float definitions. Use slower SCJet class for with double types and rapidity, similar to the LHC approach. This class uses E-scheme to combine particles (p1+p2). More details in http://arxiv.org/pdf/hep-ph/0210022v1.pdf.

Constructor Summary

Constructors

Constructor and Description
KTjet(double R, double minpt) Initialize calculations of the KT algorithm.
KTjet(double R, int recom, double minpt) Initialize calculations of the KT algorithm.
KTjet(double R, int recom, int mode, double minpt) Initialize calculations of the longitudinally invariant kT algorithm in inclusive mode.

Method Summary

Modifier and Type	Method and Description
ArrayList<ParticleF>	buildJets(ArrayList<ParticleF> list) Run the jet algorithm using the list of particles
float	getDistance(ParticleF a, ParticleF b) Calculate R distance in eta-phi.
ArrayList<ParticleF>	getJetsSorted() Get jets after sorting in jet pT.
float	getKtDistance1(ParticleF a) This is the KT distance to the beam (assuming Z=Y=0).
float	getKtDistance12(ParticleF a, ParticleF b) Calculate delta R distance.
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

KTjet

public KTjet(double R,
             int recom,
             int mode,
             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 Eta (pseudorapidity) and Phi.

Parameters:

R - distance measure

recom - recombination scheme.
1: The E-scheme Simple 4-vector addition.
2: The pT-scheme.
3: The pT^2 scheme.
Currently only E-scheme is implemented.

mode - clustering mode dij=min(kT_i^{2* mode},kT_j^{2* mode})).
mode=1 means inclusive KT jet algorithm
mode=0 means Cambridge/Aachen jet algorithm
mode=-1 means anti-KT jet algorithm

minpt - min pT for final jets.

KTjet

public KTjet(double R,
             int recom,
             double minpt)

Initialize calculations of the KT algorithm. Meaningful values are R=0.2- 1. Jets are clustered in Eta (pseudorapidity) and Phi space.

Parameters:

R - distance measure

recom - recombination scheme.
1: The E-scheme Simple 4-vector addition.
2: The pT-scheme.
3: The pT^2 scheme.
Currently only E-scheme is implemented.

minpt - min pT for final jets.

KTjet

public KTjet(double R,
             double minpt)

Initialize calculations of the KT algorithm. Meaningful values are R=0.2- 1. Jets are clustered in Eta (pseudorapidity) and Phi space. The The E-scheme with 4-vector addition is used.

Parameters:

R - distance measure

minpt - min pT for final jets.

Method Detail

buildJets

public ArrayList<ParticleF> buildJets(ArrayList<ParticleF> list)

Run the jet algorithm using the list of particles

Parameters:

list - list with particles

Returns:

final jets without sorting.

getJetsSorted

public ArrayList<ParticleF> 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

getKtDistance12

public float getKtDistance12(ParticleF a,
                             ParticleF b)

Calculate delta R distance.

Parameters:

a - input particle

b - input particle

p - power parameter

Returns:

Kt distance

getDistance

public float getDistance(ParticleF a,
                         ParticleF b)

Calculate R distance in eta-phi.

Parameters:

a - input particle

b - input particle

Returns:

eta-phi distance

getKtDistance1

public float getKtDistance1(ParticleF a)

This is the KT distance to the beam (assuming Z=Y=0). The distance measure depends on the mode parameter.

Parameters:

a - particle

Returns:

kT distance

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.

main

public static void main(String[] args)

Main class for testing.

Parameters:

args -