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BESIII_2023_I2702517

$\psi(2S)\to \Lambda \bar{\Lambda}\eta^\prime$
Experiment: BESIII (BEPC)
Inspire ID: 2702517
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References: Beams: * *
Beam energies: ANY
Run details:
  • Any process producing psi(2S) originally e+e-

Measurement of the mass distributions in the decay $\psi(2S)\to \Lambda \bar{\Lambda}\eta^\prime$. The data were read from the plots in the paper. It is also not clear that any resolution effects have been unfolded.

Source code: BESIII_2023_I2702517.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/UnstableParticles.hh"
 4#include "Rivet/Projections/DecayedParticles.hh"
 5
 6namespace Rivet {
 7
 8
 9  /// @brief psi(2S) -> Lambda Lambdabar eta'
10  class BESIII_2023_I2702517 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2023_I2702517);
15
16
17    /// @name Analysis methods
18    /// @{
19
20    /// Book histograms and initialise projections before the run
21    void init() {
22      UnstableParticles ufs = UnstableParticles(Cuts::pid==100443);
23      declare(ufs, "UFS");
24      DecayedParticles psi(ufs);
25      psi.addStable(PID::PI0);
26      psi.addStable(PID::K0S);
27      psi.addStable(PID::ETA);
28      psi.addStable(PID::ETAPRIME);
29      psi.addStable(PID::OMEGA);
30      psi.addStable( 3122);
31      psi.addStable(-3122);
32      declare(psi, "psi");
33      for (unsigned int ix=0; ix<2; ++ix) {
34        for (unsigned int iy=0; iy<2; ++iy) {
35          book(_h[ix][iy], 1+ix, 1, 1+iy);
36        }
37      }
38    }
39
40
41    /// Perform the per-event analysis
42    void analyze(const Event& event) {
43      DecayedParticles psi = apply<DecayedParticles>(event, "psi");
44      // loop over particles
45      for (unsigned int ix=0;ix<psi.decaying().size();++ix) {
46       	if (!psi.modeMatches(ix,3,mode)) continue;
47       	const Particle& eta  = psi.decayProducts()[ix].at( 331)[0];
48       	const Particle& lam  = psi.decayProducts()[ix].at( 3122)[0];
49       	const Particle& lbar = psi.decayProducts()[ix].at(-3122)[0];
50        for (unsigned int iy=0; iy<2; ++iy) {
51          _h[0][iy]->fill((lbar.mom()+eta .mom()).mass());
52          _h[0][iy]->fill((lam .mom()+eta .mom()).mass());
53          _h[1][iy]->fill((lam .mom()+lbar.mom()).mass());
54        }
55      }
56    }
57
58
59    /// Normalise histograms etc., after the run
60    void finalize() {
61      for (unsigned int ix=0;ix<2;++ix) {
62        normalize(_h[ix],1.,false);
63      }
64    }
65
66    /// @}
67
68
69    /// @name Histograms
70    /// @{
71    Histo1DPtr _h[2][2];
72    const map<PdgId,unsigned int> mode = { { 3122,1}, {-3122,1}, { 331,1} };
73    /// @}
74
75
76  };
77
78
79  RIVET_DECLARE_PLUGIN(BESIII_2023_I2702517);
80
81}