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(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); }