API documentation of the 'hephysics.jet.SCJet' Java class
SCJet
hephysics.jet

Class SCJet

SCJet
hephysics.jet

Class SCJet



  • public class SCJetextends Object
    SCJet 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 FastJet http://fastjet.fr/ implementation that uses rapidity. Use light-weight KTjet class when using pseudo-rapidity and phi to define distance parameters. The method uses E-scheme to combine particles (p1+p2). More details is in http://arxiv.org/pdf/hep-ph/0210022v1.pdf.
    • Constructor Detail

      • SCJet

        public SCJet(double R,             int recom,             int mode,             double minpt,             boolean isfast)
        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.
        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.
        isfast - if true, use a seeded anti-KT algorithm. This algorithm is faster, but some difference may exist with the original anti-KT (i.e. when true is set) for soft jets. If false, use the traditional that scales as N^3 (slow).
      • SCJet

        public SCJet(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 rapidity and phi. Fast mode is disabled.
        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.
      • SCJet

        public SCJet(double R,             double minpt)
        Initialize calculations of the kT algorithm. Meaningful values are R=0.2- 1. Jets are clustered in rapidity 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 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
      • getKtDistance12

        public double getKtDistance12(ParticleD a,                              ParticleD b)
        Calculate delta R distance.
        Parameters:
        a - input particle
        b - input particle
        p - power parameter
        Returns:
        Kt distance
      • getDistance

        public double getDistance(ParticleD a,                          ParticleD b)
        Calculate R distance in y-phi.
        Parameters:
        a - input particle
        b - input particle
        Returns:
        y-phi distance
      • getKtDistance1

        public double getKtDistance1(ParticleD 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 -

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