rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

BESIII_2019_I1724880

Charge particle multiplicity in $\eta_c$ decays
Experiment: BESIII (BEPC)
Inspire ID: 1724880
Status: VALIDATED
Authors:
  • Peter Richardson
References: Beams: * *
Beam energies: ANY
Run details:
  • Any process producing eta_c mesons

Measurememt of the charged particle multiplicity distribution in $\eta_c$ decays by the BESIII collaboration.

Source code: BESIII_2019_I1724880.cc
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief Add a short analysis description here
  class BESIII_2019_I1724880 : public Analysis {
  public:

    /// Constructor
    DEFAULT_RIVET_ANALYSIS_CTOR(BESIII_2019_I1724880);


    /// @name Analysis methods
    //@{

    /// Book histograms and initialise projections before the run
    void init() {

      // Initialise and register projections
      declare(UnstableParticles(), "UFS");

      // Book histograms
      book(_h_n, 1, 1, 1);

    }
    
    void findChildren(const Particle & p,int & nCharged) {
      for( const Particle &child : p.children()) {
	if(child.children().empty()) {
	  if(PID::isCharged(child.pid())) ++nCharged;
	}
	else
	  findChildren(child,nCharged);
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      for (const Particle& p :  apply<FinalState>(event, "UFS").particles(Cuts::pid==441)) {
	int nCharged(0);
	findChildren(p,nCharged);
	_h_n->fill(min(nCharged,8));
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_n,2.);
    }

    //@}


    /// @name Histograms
    //@{
    Histo1DPtr _h_n;
    //@}


  };


  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(BESIII_2019_I1724880);


}