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BESIII_2022_I2166759

$J/\psi$ and $\psi(2S)$ decays to $\eta\Sigma^+\bar\Sigma^-$
Experiment: BESIII (BEPC)
Inspire ID: 2166759
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References: Beams: * *
Beam energies: ANY
Run details:
  • Any process producing J/psi or psi(2S), originally e+e-

Measurements of mass distributions in $J/\psi$ and $\psi(2S)$ decays to $\eta\Sigma^+\bar\Sigma^-$. The data were read from the plots in the paper and may not be corrected for efficiency but the background given in the paper has been subtracted.

Source code: BESIII_2022_I2166759.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 J/.psi anbd psi(2S) -> eta Sigma+ Sigmabar-
10  class BESIII_2022_I2166759 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2022_I2166759);
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==443 or
23						Cuts::pid==100443);
24      declare(ufs, "UFS");
25      DecayedParticles psi(ufs);
26      psi.addStable( PID::ETA);
27      psi.addStable( PID::SIGMAPLUS);
28      psi.addStable( PID::SIGMAMINUS);
29      psi.addStable(-PID::SIGMAPLUS);
30      psi.addStable(-PID::SIGMAMINUS);
31      declare(psi, "psi");
32      // histos
33      for(unsigned int ix=0;ix<6;++ix)
34	book(_h[ix],1,1,1+ix);
35    }
36
37
38    /// Perform the per-event analysis
39    void analyze(const Event& event) {
40      static const map<PdgId,unsigned int> & mode = { { 3222,1}, {-3222,1}, { 221,1} };
41      DecayedParticles psi = apply<DecayedParticles>(event, "psi");
42      for(unsigned int ix=0;ix<psi.decaying().size();++ix) {
43	if(!psi.modeMatches(ix,3,mode)) continue;
44	unsigned int ioff = psi.decaying()[ix].pid()==443 ?  0 : 3;
45	const Particle & sigp = psi.decayProducts()[ix].at( 3222)[0];
46	const Particle & sigm = psi.decayProducts()[ix].at(-3222)[0];
47	const Particle & eta  = psi.decayProducts()[ix].at(  221)[0];
48	_h[ioff+0]->fill((sigp.momentum()+eta .momentum()).mass());
49	_h[ioff+1]->fill((sigm.momentum()+eta .momentum()).mass());
50	_h[ioff+2]->fill((sigp.momentum()+sigm.momentum()).mass());
51      }
52    }
53
54
55    /// Normalise histograms etc., after the run
56    void finalize() {
57      for(unsigned int ix=0;ix<6;++ix)
58	normalize(_h[ix],1.,false);
59    }
60
61    /// @}
62
63
64    /// @name Histograms
65    /// @{
66    Histo1DPtr _h[6];
67    /// @}
68
69
70  };
71
72
73  RIVET_DECLARE_PLUGIN(BESIII_2022_I2166759);
74
75}