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 chi_cJ -> 4KS0
10  class BESIII_2019_I1716627 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2019_I1716627);
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==20443 or
23						Cuts::pid==445   or
24						Cuts::pid==10441);
25      declare(ufs, "UFS");
26      DecayedParticles chi(ufs);
27      chi.addStable( PID::PI0);
28      chi.addStable( PID::K0S);
29      chi.addStable( PID::ETA);
30      declare(chi, "chi");
31      for(unsigned int iy=0;iy<2;++iy) {
32	book(_h[iy],1,1,1+iy);
33      }
34    }
35
36
37    /// Perform the per-event analysis
38    void analyze(const Event& event) {
39      static const map<PdgId,unsigned int> & mode   = { {310,4} };
40      DecayedParticles chi = apply<DecayedParticles>(event, "chi");
41      // loop over particles
42      for(unsigned int ix=0;ix<chi.decaying().size();++ix) {
43       	if(!chi.modeMatches(ix,4,mode)) continue;
44	const Particles & K0   = chi.decayProducts()[ix].at(310);
45	for(unsigned int iy=0;iy<4;++iy) {
46	  _h[1]->fill((chi.decaying()[ix].momentum()-K0[iy].momentum()).mass());
47	  for(unsigned int iz=ix+1;iz<4;++iz)
48	    _h[0]->fill((K0[ix].momentum()+K0[iz].momentum()).mass());
49	}
50      }
51    }
52
53
54    /// Normalise histograms etc., after the run
55    void finalize() {
56      for(unsigned int iy=0;iy<2;++iy) {
57	normalize(_h[iy]);
58      }
59    }
60
61    /// @}
62
63
64    /// @name Histograms
65    /// @{
66    Histo1DPtr _h[2];
67    /// @}
68
69
70  };
71
72
73  RIVET_DECLARE_PLUGIN(BESIII_2019_I1716627);
74
75}