1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/UnstableParticles.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief J/Psi chi_c charged particle multiplicities
 9  class BESIII_2020_I1800404 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2020_I1800404);
14
15
16    /// @name Analysis methods
17    /// @{
18
19    /// Book histograms and initialise projections before the run
20    void init() {
21      // Initialise and register projections
22      declare(UnstableParticles(Cuts::pid==443 or Cuts::pid==445 or Cuts::pid==10441 or Cuts::pid==20443),"UFS");
23      // histograms
24      book(_h_chi0,1,1,1);
25      book(_h_chi1,1,1,2);
26      book(_h_chi2,1,1,3);
27      book(_h_jpsi[0],2,1,1);
28      book(_h_jpsi[1],2,1,2);
29    }
30
31    void findChildren(const Particle & p, int & nCharged) {
32      for( const Particle &child : p.children()) {
33        if(child.children().empty()) {
34          if(PID::isCharged(child.pid())) ++nCharged;
35        }
36        else
37          findChildren(child,nCharged);
38      }
39    }
40
41    /// Perform the per-event analysis
42    void analyze(const Event& event) {
43      // loop over particles
44      for( const Particle & p : apply<UnstableParticles>(event, "UFS").particles()) {
45        // skip radiative modes
46        if(p.children().size()==2) {
47          if(p.children()[0].pid()==PID::GAMMA) {
48            if(p.children()[1].pid()==PID::GAMMA ||
49               p.children()[1].pid()==PID::JPSI) continue;
50          }
51          if(p.children()[1].pid()==PID::GAMMA) {
52            if(p.children()[0].pid()==PID::GAMMA ||
53               p.children()[0].pid()==PID::JPSI) continue;
54          }
55        }
56        // get the charged particle multiplicity
57        int nCharged(0);
58        findChildren(p,nCharged);
59        if(p.pid()==PID::JPSI) {
60          _h_jpsi[0]->fill(nCharged);
61          _h_jpsi[1]->fill(nCharged);
62        }
63        else if(p.pid()==10441)
64          _h_chi0->fill(nCharged);
65        else if(p.pid()==20443)
66          _h_chi1->fill(nCharged);
67        else if(p.pid()==445)
68          _h_chi2->fill(nCharged);
69      }
70    }
71
72
73    /// Normalise histograms etc., after the run
74    void finalize() {
75      // percentage and bin width
76      normalize(_h_jpsi[0],200.);
77      normalize(_h_jpsi[1],200.);
78      normalize(_h_chi0   ,200.);
79      normalize(_h_chi1   ,200.);
80      normalize(_h_chi2   ,200.);
81    }
82
83    /// @}
84
85
86    /// @name Histograms
87    /// @{
88    Histo1DPtr _h_jpsi[2],_h_chi0,_h_chi1,_h_chi2;
89    /// @}
90
91  };
92
93
94  RIVET_DECLARE_PLUGIN(BESIII_2020_I1800404);
95
96}