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

All Methods Static Methods Instance Methods Concrete Methods
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 -

Class JetN2

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

JetN2

JetN2

JetN2

JetN2

Method Detail

buildJets

getJetsSorted

printJets

toString

setDebug

info

main