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DELPHI_2003_I628566

Spectrum for $f_1(1285)$ and $f_1^\prime(1420)$ production in hadronic $Z^0$ decays
Experiment: DELPHI (LEP)
Inspire ID: 628566
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • Phys.Lett.B 569 (2003) 129-139
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)

DELPHI results for the spectrum for $f_1(1285)$ and $f_1^\prime(1420)$ production in hadronic $Z^0$ decays

Source code: DELPHI_2003_I628566.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4#include "Rivet/Projections/ChargedFinalState.hh"
 5#include "Rivet/Projections/UnstableParticles.hh"
 6#include "Rivet/Projections/Beam.hh"
 7
 8namespace Rivet {
 9
10
11  /// @brief f_1 and f'_1 spectra
12  class DELPHI_2003_I628566 : public Analysis {
13  public:
14
15    /// Constructor
16    RIVET_DEFAULT_ANALYSIS_CTOR(DELPHI_2003_I628566);
17
18
19    /// @name Analysis methods
20    /// @{
21
22    /// Book histograms and initialise projections before the run
23    void init() {
24      declare(Beam(), "Beams");
25      declare(ChargedFinalState(), "FS");
26      declare(UnstableParticles(Cuts::pid==20223 || Cuts::pid==20333), "UFS");
27
28      // Book histograms
29      book(_n_f1     , 1, 1, 1);
30      book(_n_f1prime, 1, 1, 2);
31      book(_h_f1     , 2, 1, 1);
32      book(_h_f1prime, 2, 1, 2);
33    }
34
35
36    /// Perform the per-event analysis
37    void analyze(const Event& event) {
38
39      // First, veto on leptonic events by requiring at least 4 charged FS particles
40      const FinalState& fs = apply<FinalState>(event, "FS");
41      const size_t numParticles = fs.particles().size();
42
43      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
44      if (numParticles < 2) {
45        MSG_DEBUG("Failed leptonic event cut");
46        vetoEvent;
47      }
48      MSG_DEBUG("Passed leptonic event cut");
49
50      // Get beams and average beam momentum
51      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
52      const double meanBeamMom = 0.5*(beams.first.p3().mod() + beams.second.p3().mod());
53      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
54
55      // Final state of unstable particles to get particle spectra
56      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
57
58      for (const Particle& p : ufs.particles()) {
59        const double xp = p.p3().mod()/meanBeamMom;
60        if (p.pid()==20223) {
61          _n_f1->fill("91.2"s);
62          _h_f1->fill(xp);
63        }
64        else {
65          _n_f1prime->fill("91.2"s);
66          _h_f1prime->fill(xp);
67        }
68      }
69    }
70
71
72    /// Normalise histograms etc., after the run
73    void finalize() {
74      scale(_n_f1     , 1./sumOfWeights());
75      scale(_n_f1prime, 1./sumOfWeights());
76      scale(_h_f1     , 1./sumOfWeights());
77      scale(_h_f1prime, 1./sumOfWeights());
78    }
79
80    /// @}
81
82
83    /// @name Histograms
84    /// @{
85    BinnedHistoPtr<string> _n_f1,_n_f1prime;
86    Histo1DPtr _h_f1,_h_f1prime;
87    /// @}
88
89
90  };
91
92
93  RIVET_DECLARE_PLUGIN(DELPHI_2003_I628566);
94
95}