Rivet analyses referenceOPAL_1996_I402487$J/\psi$ and $\psi^\prime$ Production in Hadronic $Z^0$ DecaysExperiment: OPAL (LEP 1) Inspire ID: 402487 Status: VALIDATED Authors:
Beam energies: (45.6, 45.6) GeV Run details:
The production of $J/\psi$ and $\psi^\prime$ mesons measured by the OPAL experiment at LEP. The fragmentation function for $J/\psi$ and the multiplicities of $J/\psi$ and $\psi^\prime$ are included. Source code: OPAL_1996_I402487.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/Beam.hh"
4#include "Rivet/Projections/FinalState.hh"
5#include "Rivet/Projections/ChargedFinalState.hh"
6#include "Rivet/Projections/UnstableParticles.hh"
7
8namespace Rivet {
9
10
11 /// @brief OPAL J/Psi fragmentation function paper
12 ///
13 /// @author Peter Richardson
14 class OPAL_1996_I402487 : public Analysis {
15 public:
16
17 RIVET_DEFAULT_ANALYSIS_CTOR(OPAL_1996_I402487);
18
19
20 /// @name Analysis methods
21 /// @{
22
23 void init() {
24 declare(Beam(), "Beams");
25 declare(ChargedFinalState(), "FS");
26 declare(UnstableParticles(), "UFS");
27 book(_histXpJPsi , 1, 1, 1);
28 book(_multJPsi , 2, 1, 1);
29 book(_multPsiPrime , 2, 1, 2);
30 book(_weightSum,"_weightSum");
31 }
32
33
34 void analyze(const Event& e) {
35 // First, veto on leptonic events by requiring at least 4 charged FS particles
36 const FinalState& fs = apply<FinalState>(e, "FS");
37 const size_t numParticles = fs.particles().size();
38
39 // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
40 if (numParticles < 2) {
41 MSG_DEBUG("Failed leptonic event cut");
42 vetoEvent;
43 }
44 MSG_DEBUG("Passed leptonic event cut");
45
46 // Get beams and average beam momentum
47 const ParticlePair& beams = apply<Beam>(e, "Beams").beams();
48 const double meanBeamMom = ( beams.first.p3().mod() +
49 beams.second.p3().mod() ) / 2.0;
50 MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
51
52 // Final state of unstable particles to get particle spectra
53 const UnstableParticles& ufs = apply<UnstableParticles>(e, "UFS");
54
55 for (const Particle& p : ufs.particles()) {
56 if(p.abspid()==443) {
57 double xp = p.p3().mod()/meanBeamMom;
58 _histXpJPsi->fill(xp);
59 _multJPsi->fill(91.2);
60 _weightSum->fill();
61 }
62 else if(p.abspid()==100443) {
63 _multPsiPrime->fill(91.2);
64 }
65 }
66 }
67
68
69 /// Finalize
70 void finalize() {
71 if(_weightSum->val()>0.)
72 scale(_histXpJPsi , 0.1/ *_weightSum);
73 scale(_multJPsi , 1./sumOfWeights());
74 scale(_multPsiPrime, 1./sumOfWeights());
75 }
76
77 /// @}
78
79
80 /// @{
81 CounterPtr _weightSum;
82 Histo1DPtr _histXpJPsi;
83 Histo1DPtr _multJPsi;
84 Histo1DPtr _multPsiPrime;
85 /// @}
86
87 };
88
89
90
91 RIVET_DECLARE_ALIASED_PLUGIN(OPAL_1996_I402487, OPAL_1996_S3257789);
92
93}
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