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 K- e+ nu_e
10  class BESIII_2022_I2122399 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2022_I2122399);
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::pid==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::ETAPRIME);
30      declare(LambdaC, "LambdaC");
31      
32      // Book histogram
33      book(_h,1,1,1);
34    }
35
36
37    /// Perform the per-event analysis
38    void analyze(const Event& event) {
39      static const map<PdgId,unsigned int> & mode = { { -321,1}, { 2212,1}, {-11,1}, { 12,1}};
40      DecayedParticles LambdaC = apply<DecayedParticles>(event, "LambdaC");
41      // loop over particles
42      for(unsigned int ix=0;ix<LambdaC.decaying().size();++ix) {
43	if ( !LambdaC.modeMatches(ix,4,mode) ) continue;
44       	const Particle & Km = LambdaC.decayProducts()[ix].at(-321 )[0];
45       	const Particle & pp = LambdaC.decayProducts()[ix].at( 2212)[0];
46	_h->fill((Km.momentum()+pp.momentum()).mass());
47      }
48    }
49
50
51    /// Normalise histograms etc., after the run
52    void finalize() {
53      normalize(_h,1.,false);
54    }
55
56    /// @}
57
58
59    /// @name Histograms
60    /// @{
61    Histo1DPtr _h;
62    /// @}
63
64
65  };
66
67
68  RIVET_DECLARE_PLUGIN(BESIII_2022_I2122399);
69
70}