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 B+ -> phi phi K+
10  class BELLE_2021_I1841899 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2021_I1841899);
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==521);
24      declare(ufs, "UFS");
25      DecayedParticles BP(ufs);
26      BP.addStable(PID::PI0);
27      BP.addStable(PID::K0S);
28      BP.addStable(PID::ETA);
29      BP.addStable(PID::ETAPRIME);
30      BP.addStable(PID::PHI);
31      declare(BP, "BP");
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      // define the decay mode
41      static const map<PdgId,unsigned int> & mode   = { { 321,1},{ 333,2}};
42      static const map<PdgId,unsigned int> & modeCC = { {-321,1},{ 333,2}};
43      DecayedParticles BP = apply<DecayedParticles>(event, "BP");
44      // loop over particles
45      for(unsigned int ix=0;ix<BP.decaying().size();++ix) {
46	int sign = 1;
47	if (BP.decaying()[ix].pid()>0 && BP.modeMatches(ix,3,mode)) {
48	  sign=1;
49	}
50	else if  (BP.decaying()[ix].pid()<0 && BP.modeMatches(ix,3,modeCC)) {
51	  sign=-1;
52	}
53	else
54	  continue;
55	const Particles & Kp  = BP.decayProducts()[ix].at( sign*321);
56	const Particles & phi = BP.decayProducts()[ix].at(      333);
57	_h[0]->fill((phi[0].momentum()+phi[1].momentum()).mass());
58	_h[1]->fill((Kp [0].momentum()+phi[0].momentum()).mass());
59	_h[1]->fill((Kp [0].momentum()+phi[1].momentum()).mass());
60      }
61    }
62
63
64    /// Normalise histograms etc., after the run
65    void finalize() {
66      for(unsigned int ix=0;ix<2;++ix)
67	normalize(_h[ix],1.,false);
68    }
69
70    /// @}
71
72
73    /// @name Histograms
74    /// @{
75    Histo1DPtr _h[2];
76    /// @}
77
78
79  };
80
81
82  RIVET_DECLARE_PLUGIN(BELLE_2021_I1841899);
83
84}