rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

DELPHI_1995_S3137023

Strange baryon production in $Z$ hadronic decays at Delphi
Experiment: DELPHI (LEP 1)
Inspire ID: 394716
Status: VALIDATED
Authors:
  • Hendrik Hoeth
References:
  • Z. Phys. C, 67, 543--554 (1995)
Beams: e+ e-
Beam energies: (45.6, 45.6) GeV
Run details:
  • Hadronic Z decay events generated on the Z pole ($\sqrt{s} = 91.2$ GeV)

Measurement of the $\Xi^-$ and $\Sigma^+(1385)/\Sigma^-(1385)$ scaled momentum distributions by DELPHI at LEP 1. The paper also has the production cross-sections of these particles, but that's not implemented in Rivet.

Source code: DELPHI_1995_S3137023.cc
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/Beam.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/UnstableFinalState.hh"

namespace Rivet {


  /// @brief DELPHI strange baryon paper
  /// @author Hendrik Hoeth
  class DELPHI_1995_S3137023 : public Analysis {
  public:

    /// Constructor
    DELPHI_1995_S3137023()
      : Analysis("DELPHI_1995_S3137023")
    {
      _weightedTotalNumXiMinus = 0;
      _weightedTotalNumSigma1385Plus = 0;
    }


    /// @name Analysis methods
    //@{

    void init() {
      declare(Beam(), "Beams");
      declare(ChargedFinalState(), "FS");
      declare(UnstableFinalState(), "UFS");

      _histXpXiMinus       = bookHisto1D(2, 1, 1);
      _histXpSigma1385Plus = bookHisto1D(3, 1, 1);
    }


    void analyze(const Event& e) {
      // First, veto on leptonic events by requiring at least 4 charged FS particles
      const FinalState& fs = apply<FinalState>(e, "FS");
      const size_t numParticles = fs.particles().size();

      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
      if (numParticles < 2) {
        MSG_DEBUG("Failed leptonic event cut");
        vetoEvent;
      }
      MSG_DEBUG("Passed leptonic event cut");

      // Get event weight for histo filling
      const double weight = e.weight();

      // Get beams and average beam momentum
      const ParticlePair& beams = apply<Beam>(e, "Beams").beams();
      const double meanBeamMom = ( beams.first.p3().mod() +
                                   beams.second.p3().mod() ) / 2.0;
      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);

      // Final state of unstable particles to get particle spectra
      const UnstableFinalState& ufs = apply<UnstableFinalState>(e, "UFS");

      foreach (const Particle& p, ufs.particles()) {
        const int id = p.abspid();
        switch (id) {
        case 3312:
          _histXpXiMinus->fill(p.p3().mod()/meanBeamMom, weight);
          _weightedTotalNumXiMinus += weight;
          break;
        case 3114: case 3224:
          _histXpSigma1385Plus->fill(p.p3().mod()/meanBeamMom, weight);
          _weightedTotalNumSigma1385Plus += weight;
          break;
        }
      }

    }


    /// Finalize
    void finalize() {
      normalize(_histXpXiMinus       , _weightedTotalNumXiMinus/sumOfWeights());
      normalize(_histXpSigma1385Plus , _weightedTotalNumSigma1385Plus/sumOfWeights());
    }

    //@}


  private:

    /// Store the weighted sums of numbers of charged / charged+neutral
    /// particles - used to calculate average number of particles for the
    /// inclusive single particle distributions' normalisations.
    double _weightedTotalNumXiMinus;
    double _weightedTotalNumSigma1385Plus;

    Histo1DPtr _histXpXiMinus;
    Histo1DPtr _histXpSigma1385Plus;
    //@}

  };



  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(DELPHI_1995_S3137023);

}