Rivet analyses

Mass distributions in τ decays with KS0 mesons

Experiment: CLEOII (CESR)

Inspire ID: 415408

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 53 (1996) 6037-6053

Beams: * *

Beam energies: ANY

Run details: - Any process producing tau leptons, originally e+e-

Mass distributions in the decays τ → ντ + KS0π−, K−KS0, KS0π−π0, KS0K−π0 and KS0KS0π−. The background subtracted data were read from the figures in the paper.

Source code:CLEOII_1996_I415408.cc

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/DecayedParticles.hh"
#include "Rivet/Projections/UnstableParticles.hh"


namespace Rivet {


  /// @brief tau -> hadrons with KS0
  class CLEOII_1996_I415408 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_1996_I415408);


    /// @name Analysis methods
    /// @{

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 15);
      declare(ufs, "UFS");
      DecayedParticles TAU(ufs);
      TAU.addStable(310);
      TAU.addStable(111);
      declare(TAU, "TAU");
      // histos
      for (unsigned int ix = 0; ix < 4; ++ix) {
        book(_h[ix], 1 + ix, 1, 1);
        if (ix > 1) continue;
        book(_h[4 + ix], 5, 1, 1 + ix);
        book(_h[6 + ix], 6 + ix, 1, 1);
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      DecayedParticles TAU = apply<DecayedParticles>(event, "TAU");
      // loop over particles
      for (unsigned int ix = 0; ix < TAU.decaying().size(); ++ix) {
        int sign = TAU.decaying()[ix].pid() > 0 ? 1 : -1;
        if ((TAU.modeMatches(ix, 3, mode1) || TAU.modeMatches(ix, 3, mode1CC))) {
          const Particle& pim = TAU.decayProducts()[ix].at(-211 * sign)[0];
          const Particle& K0 = TAU.decayProducts()[ix].at(310)[0];
          _h[0]->fill((pim.mom() + K0.mom()).mass());
        }
        else if (TAU.modeMatches(ix, 3, mode2) || TAU.modeMatches(ix, 3, mode2CC)) {
          const Particle& Km = TAU.decayProducts()[ix].at(-321 * sign)[0];
          const Particle& K0 = TAU.decayProducts()[ix].at(310)[0];
          _h[1]->fill((Km.mom() + K0.mom()).mass());
        }
        else if (TAU.modeMatches(ix, 4, mode3) || TAU.modeMatches(ix, 4, mode3CC)) {
          const Particle& pim = TAU.decayProducts()[ix].at(-211 * sign)[0];
          const Particle& K0 = TAU.decayProducts()[ix].at(310)[0];
          const Particle& pi0 = TAU.decayProducts()[ix].at(111)[0];
          _h[2]->fill((pim.mom() + K0.mom() + pi0.mom()).mass());
        }
        else if (TAU.modeMatches(ix, 4, mode4) || TAU.modeMatches(ix, 4, mode4CC)) {
          const Particle& Km = TAU.decayProducts()[ix].at(-321 * sign)[0];
          const Particle& K0 = TAU.decayProducts()[ix].at(310)[0];
          const Particle& pi0 = TAU.decayProducts()[ix].at(111)[0];
          _h[3]->fill((Km.mom() + K0.mom() + pi0.mom()).mass());
          _h[4]->fill((Km.mom() + pi0.mom()).mass());
          _h[5]->fill((K0.mom() + pi0.mom()).mass());
        }
        else if (TAU.modeMatches(ix, 4, mode5) || TAU.modeMatches(ix, 4, mode5CC)) {
          const Particle& pim = TAU.decayProducts()[ix].at(-211 * sign)[0];
          const Particles& K0 = TAU.decayProducts()[ix].at(310);
          _h[6]->fill((pim.mom() + K0[0].mom() + K0[1].mom()).mass());
          _h[7]->fill((pim.mom() + K0[0].mom()).mass());
          _h[7]->fill((pim.mom() + K0[1].mom()).mass());
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h, 1.0, false);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[8];
    const map<PdgId, unsigned int> mode1 = {{310, 1}, {-211, 1}, {16, 1}};
    const map<PdgId, unsigned int> mode1CC = {{310, 1}, {211, 1}, {-16, 1}};
    const map<PdgId, unsigned int> mode2 = {{310, 1}, {-321, 1}, {16, 1}};
    const map<PdgId, unsigned int> mode2CC = {{310, 1}, {321, 1}, {-16, 1}};
    const map<PdgId, unsigned int> mode3 = {{310, 1}, {-211, 1}, {111, 1}, {16, 1}};
    const map<PdgId, unsigned int> mode3CC = {{310, 1}, {211, 1}, {111, 1}, {-16, 1}};
    const map<PdgId, unsigned int> mode4 = {{310, 1}, {-321, 1}, {111, 1}, {16, 1}};
    const map<PdgId, unsigned int> mode4CC = {{310, 1}, {321, 1}, {111, 1}, {-16, 1}};
    const map<PdgId, unsigned int> mode5 = {{310, 2}, {-211, 1}, {16, 1}};
    const map<PdgId, unsigned int> mode5CC = {{310, 2}, {211, 1}, {-16, 1}};
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CLEOII_1996_I415408);

}