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BESIII_2021_I1837968

Mass distributions in $\Lambda_c^+\to p K^0_S \eta$
Experiment: BESIII (BEPC)
Inspire ID: 1837968
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • Phys.Lett.B 817 (2021) 136327
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing Lambda_c+ mesons

Measurement of the mass distributions in the decay $\Lambda_c^+\to p K^0_S \eta$ by BESIII. The data were read from the plots in the paper and may not have been corrected for efficiency/acceptance.

Source code: BESIII_2021_I1837968.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 Lambda_c+ -> p K0S eta
10  class BESIII_2021_I1837968 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2021_I1837968);
15
16
17    /// @name Analysis methods
18    /// @{
19
20    /// Book histograms and initialise projections before the run
21    void init() {
22      // Initialise and register projections
23      UnstableParticles ufs = UnstableParticles(Cuts::abspid==4122);
24      declare(ufs, "UFS");
25      DecayedParticles LAMBDAC(ufs);
26      LAMBDAC.addStable(PID::PI0);
27      LAMBDAC.addStable(PID::K0S);
28      LAMBDAC.addStable(PID::ETA);
29      declare(LAMBDAC, "LAMBDAC");
30      // histograms
31      for(unsigned int ix=0;ix<3;++ix)
32	book(_h[ix],1,1,1+ix);
33    }
34
35
36    /// Perform the per-event analysis
37    void analyze(const Event& event) {
38      static const map<PdgId,unsigned int> & mode   = { { PID::PROTON,1}, {310,1}, { 221,1}};
39      static const map<PdgId,unsigned int> & modeCC = { {-PID::PROTON,1}, {310,1}, { 221,1}};
40      DecayedParticles LAMBDAC = apply<DecayedParticles>(event, "LAMBDAC");
41      // loop over particles
42      for(unsigned int ix=0;ix<LAMBDAC.decaying().size();++ix) {
43	int sign = 1;
44	if (LAMBDAC.decaying()[ix].pid()>0 && LAMBDAC.modeMatches(ix,3,mode)) {
45	  sign=1;
46	}
47	else if  (LAMBDAC.decaying()[ix].pid()<0 && LAMBDAC.modeMatches(ix,3,modeCC)) {
48	  sign=-1;
49	}
50	else
51	  continue;
52	const Particle & pp  = LAMBDAC.decayProducts()[ix].at( sign*PID::PROTON)[0];
53	const Particle & eta = LAMBDAC.decayProducts()[ix].at( 221)[0];
54	const Particle & K0  = LAMBDAC.decayProducts()[ix].at( 310)[0];
55	_h[0]->fill((pp.momentum()+ K0.momentum()).mass());
56	_h[1]->fill((K0.momentum()+eta.momentum()).mass());
57	_h[2]->fill((pp.momentum()+eta.momentum()).mass());
58      }
59    }
60
61
62    /// Normalise histograms etc., after the run
63    void finalize() {
64      for(unsigned int ix=0;ix<3;++ix)
65	normalize(_h[ix]);
66    }
67
68    /// @}
69
70
71    /// @name Histograms
72    /// @{
73    Histo1DPtr _h[3];
74    /// @}
75
76
77  };
78
79
80  RIVET_DECLARE_PLUGIN(BESIII_2021_I1837968);
81
82}