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L3_1997_I427107

$\eta^\prime$ and $\omega$ spectra at 91 GeV
Experiment: L3 (LEP)
Inspire ID: 427107
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. B393 (1997) 465-476, 1997
Beams: e- e+
Beam energies: (45.6, 45.6) GeV
Run details:
  • e+ e- to hadrons at the Z pole

Measurement of the momentum distribution of the $\eta^\prime$ and $\omega$ mesons at 91.2 GeV in $e^+e^-$ collisions.

Source code: L3_1997_I427107.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/Beam.hh"
  4#include "Rivet/Projections/ChargedFinalState.hh"
  5#include "Rivet/Projections/UnstableParticles.hh"
  6
  7namespace Rivet {
  8
  9
 10  /// @brief eta' and omega production at mz
 11  class L3_1997_I427107 : public Analysis {
 12  public:
 13
 14    /// Constructor
 15    RIVET_DEFAULT_ANALYSIS_CTOR(L3_1997_I427107);
 16
 17
 18    /// @name Analysis methods
 19    //@{
 20
 21    /// Book histograms and initialise projections before the run
 22    void init() {
 23
 24      // Initialise and register projections
 25      declare(Beam(), "Beams");
 26      declare(ChargedFinalState(), "FS");
 27      declare(UnstableParticles(), "UFS");
 28
 29      // // Book histograms
 30      book(_histXpOmega  ,  5, 1, 1);
 31      book(_histLnXpOmega,  6, 1, 1);
 32      book(_histXpEtaP1  ,  7, 1, 1);
 33      book(_histLnXpEtaP1,  8, 1, 1);
 34      book(_histXpEtaP2  ,  9, 1, 1);
 35      book(_histLnXpEtaP2, 10, 1, 1);
 36
 37    }
 38
 39
 40    /// Perform the per-event analysis
 41    void analyze(const Event& event) {
 42
 43      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.                                                    
 44      const FinalState& fs = apply<FinalState>(event, "FS");
 45      if (fs.particles().size() < 2) {
 46      	MSG_DEBUG("Failed ncharged cut");
 47      	vetoEvent;
 48      }
 49      MSG_DEBUG("Passed ncharged cut");
 50
 51      // Get beams and average beam momentum                                                                                                
 52      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
 53      const double meanBeamMom = ( beams.first.p3().mod() + beams.second.p3().mod() ) / 2.0;
 54      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
 55
 56      // Final state of unstable particles to get particle spectra
 57      const Particles& mesons = apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==PID::ETAPRIME or
 58      										 Cuts::pid==PID::OMEGA);
 59
 60      for (const Particle& p : mesons) {
 61      	double xp = p.p3().mod()/meanBeamMom;
 62	double xi = log(1./xp);
 63      	if(p.pid()==PID::ETAPRIME) {
 64      	  _histXpEtaP1->fill(xp);
 65      	  _histLnXpEtaP1->fill(xi);
 66      	  _histXpEtaP2->fill(xp);
 67      	  _histLnXpEtaP2->fill(xi);
 68      	}
 69      	else {
 70      	  _histXpOmega->fill(xp);
 71      	  _histLnXpOmega->fill(xi);
 72      	}
 73      }
 74    }
 75
 76
 77    /// Normalise histograms etc., after the run
 78    void finalize() {
 79      scale(_histXpEtaP1  , 1./sumOfWeights());
 80      scale(_histLnXpEtaP1, 1./sumOfWeights());
 81      scale(_histXpEtaP2  , 1./sumOfWeights());
 82      scale(_histLnXpEtaP2, 1./sumOfWeights());
 83      scale(_histXpOmega  , 1./sumOfWeights());
 84      scale(_histLnXpOmega, 1./sumOfWeights());
 85    }
 86
 87    //@}
 88
 89
 90    /// @name Histograms
 91    //@{
 92    Histo1DPtr _histXpEtaP1,_histXpEtaP2;
 93    Histo1DPtr _histLnXpEtaP1,_histLnXpEtaP2;
 94    Histo1DPtr _histXpOmega;
 95    Histo1DPtr _histLnXpOmega;
 96    //@}
 97
 98
 99  };
100
101
102  // The hook for the plugin system
103  RIVET_DECLARE_PLUGIN(L3_1997_I427107);
104
105
106}