Rivet analyses referenceOPAL_1995_I398320$\Delta^{++}$ Production in Hadronic $Z^0$ DecaysExperiment: OPAL (LEP 1) Inspire ID: 398320 Status: VALIDATED Authors:
Beam energies: (45.6, 45.6) GeV Run details:
The production of $\Delta^{++}$ baryons measured using 3.5 million $Z^0$ events by the OPAL experiment at LEP. Only the fragmentation function is implemented. Source code: OPAL_1995_I398320.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 Delta++ fragmentation function paper
12 ///
13 /// @author Peter Richardson
14 class OPAL_1995_I398320 : public Analysis {
15 public:
16
17 RIVET_DEFAULT_ANALYSIS_CTOR(OPAL_1995_I398320);
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(_histXpDelta, 1, 1, 1);
28 }
29
30
31 void analyze(const Event& e) {
32 // First, veto on leptonic events by requiring at least 4 charged FS particles
33 const FinalState& fs = apply<FinalState>(e, "FS");
34 const size_t numParticles = fs.particles().size();
35
36 // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
37 if (numParticles < 2) {
38 MSG_DEBUG("Failed leptonic event cut");
39 vetoEvent;
40 }
41 MSG_DEBUG("Passed leptonic event cut");
42
43 // Get beams and average beam momentum
44 const ParticlePair& beams = apply<Beam>(e, "Beams").beams();
45 const double meanBeamMom = ( beams.first.p3().mod() +
46 beams.second.p3().mod() ) / 2.0;
47 MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
48
49 // Final state of unstable particles to get particle spectra
50 const UnstableParticles& ufs = apply<UnstableParticles>(e, "UFS");
51
52 for (const Particle& p : ufs.particles()) {
53 if(p.abspid()==2224) {
54 double xp = p.p3().mod()/meanBeamMom;
55 _histXpDelta->fill(xp);
56 }
57 }
58 }
59
60
61 /// Finalize
62 void finalize() {
63 scale(_histXpDelta, 1./sumOfWeights());
64 }
65
66 /// @}
67
68
69 private:
70
71 Histo1DPtr _histXpDelta;
72
73 };
74
75
76
77 RIVET_DECLARE_ALIASED_PLUGIN(OPAL_1995_I398320, OPAL_1995_S3198391);
78
79}
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