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Rivet analyses reference

HRS_1988_I250824

$\eta$ spectrum in $e^+e^-$ collisions at 29 GeV
Experiment: HRS (PEP)
Inspire ID: 250824
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. B205 (1988) 111-114
Beams: e+ e-
Beam energies: (14.5, 14.5) GeV
Run details:
  • Hadronic e+e- events at $\sqrt{s} = 29.$ GeV

$\eta$ meson momentum spectrum measured at $\sqrt{s} = 29.$ GeV using the HRS detector at PEP. The bin widths are not included in either the paper or HEPdata and have therefore been infered.

Source code: HRS_1988_I250824.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4#include "Rivet/Projections/UnstableParticles.hh"
 5#include "Rivet/Projections/Beam.hh"
 6
 7namespace Rivet {
 8
 9
10  /// @brief Add a short analysis description here
11  class HRS_1988_I250824 : public Analysis {
12  public:
13
14    /// Constructor
15    RIVET_DEFAULT_ANALYSIS_CTOR(HRS_1988_I250824);
16
17
18    /// @name Analysis methods
19    //@{
20
21    /// Book histograms and initialise projections before the run
22    void init() {
23      declare(Beam(), "Beams");
24      declare(FinalState(), "FS");
25      declare(UnstableParticles(), "UFS");
26
27      // Book histograms
28      book(_h_eta, 1 , 1, 1);
29    }
30
31
32    /// Perform the per-event analysis
33    void analyze(const Event& event) {
34      // First, veto on leptonic events by requiring at least 4 charged FS particles
35      const FinalState& fs = apply<FinalState>(event, "FS");
36      const size_t numParticles = fs.particles().size();
37
38      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
39      if (numParticles < 2) {
40        MSG_DEBUG("Failed leptonic event cut");
41        vetoEvent;
42      }
43      MSG_DEBUG("Passed leptonic event cut");
44
45      // Get beams and average beam momentum
46      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
47      const double meanBeamMom = ( beams.first.p3().mod() +
48                                   beams.second.p3().mod() ) / 2.0;
49      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
50
51      // Final state to get particle spectra
52      for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==221)) {
53	double xE = p.E()/meanBeamMom;
54	_h_eta->fill(xE);
55      }
56    }
57
58
59    /// Normalise histograms etc., after the run
60    void finalize() {
61
62      double fact = sqr(sqrtS())/GeV2*crossSection()/microbarn/sumOfWeights();
63      scale(_h_eta, fact); 
64    }
65
66    //@}
67
68
69    /// @name Histograms
70    //@{
71    Histo1DPtr _h_eta;
72    //@}
73
74
75  };
76
77
78  // The hook for the plugin system
79  RIVET_DECLARE_PLUGIN(HRS_1988_I250824);
80
81
82}