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BELLE_2020_I1813380

Mass distributions in $\Lambda_c^+\to \eta\Lambda\pi^+$
Experiment: BELLE (KEKB)
Inspire ID: 1813380
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • Phys.Rev.D 103 (2021) 5, 052005
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing Lambda_c+ mesons

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

Source code: BELLE_2020_I1813380.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+ -> eta Lambda pi+
10  class BELLE_2020_I1813380 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2020_I1813380);
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      LAMBDAC.addStable(PID::LAMBDA);
30      LAMBDAC.addStable(-PID::LAMBDA);
31      declare(LAMBDAC, "LAMBDAC");
32      // histograms
33      for(unsigned int ix=0;ix<2;++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   = { { PID::LAMBDA,1}, { 211,1}, { 221,1}};
41      static const map<PdgId,unsigned int> & modeCC = { {-PID::LAMBDA,1}, {-211,1}, { 221,1}};
42      DecayedParticles LAMBDAC = apply<DecayedParticles>(event, "LAMBDAC");
43      // loop over particles
44      for(unsigned int ix=0;ix<LAMBDAC.decaying().size();++ix) {
45	int sign = 1;
46	if (LAMBDAC.decaying()[ix].pid()>0 && LAMBDAC.modeMatches(ix,3,mode)) {
47	  sign=1;
48	}
49	else if  (LAMBDAC.decaying()[ix].pid()<0 && LAMBDAC.modeMatches(ix,3,modeCC)) {
50	  sign=-1;
51	}
52	else
53	  continue;
54	const Particle & lam = LAMBDAC.decayProducts()[ix].at( sign*PID::LAMBDA)[0];
55	const Particle & eta = LAMBDAC.decayProducts()[ix].at( 221)[0];
56	const Particle & pip  = LAMBDAC.decayProducts()[ix].at( sign*211)[0];
57	_h[0]->fill((lam.momentum()+eta.momentum()).mass());
58	_h[1]->fill((lam.momentum()+pip.momentum()).mass());
59      }
60    }
61
62
63    /// Normalise histograms etc., after the run
64    void finalize() {
65      for(unsigned int ix=0;ix<2;++ix)
66	normalize(_h[ix],1.,false);
67    }
68
69    /// @}
70
71
72    /// @name Histograms
73    /// @{
74    Histo1DPtr _h[2];
75    /// @}
76
77
78  };
79
80
81  RIVET_DECLARE_PLUGIN(BELLE_2020_I1813380);
82
83}