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BESIII_2010_I878544

Mass distributions in $\chi_{cJ}\to 4\pi^0$
Experiment: BESIII (BEPC)
Inspire ID: 878544
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • Phys.Rev.D 83 (2011) 012006
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing chi_c0,1,2

easurement of the mass distributions in the decays $\chi_{cJ}\to 4\pi^0$. The data were read from the plots in the paper and may not be corrected for backgrounds and efficiency.

Source code: BESIII_2010_I878544.cc
 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 -> 4 pi0
10  class BESIII_2010_I878544 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2010_I878544);
15
16
17    /// @name Analysis methods
18    /// @{
19
20    /// Book histograms and initialise projections before the run
21    void init() {
22      // projections
23      UnstableParticles ufs = UnstableParticles(Cuts::pid==10441 ||
24						Cuts::pid==445   ||
25						Cuts::pid==20443);
26      declare(ufs, "UFS");
27      DecayedParticles chi(ufs);
28      chi.addStable( PID::PI0);
29      declare(chi, "chi");
30      // histograms
31      for(unsigned int ix=0;ix<3;++ix)
32	book(_h[ix],1,1,1+ix);
33    }
34
35
36    /// Perform the per-event analysis
37    void analyze(const Event& event) {
38      static const map<PdgId,unsigned int> & mode = { { 111,4} };
39      DecayedParticles chi = apply<DecayedParticles>(event, "chi");
40      // loop over particles
41      for(unsigned int ix=0;ix<chi.decaying().size();++ix) {
42	if(!chi.modeMatches(ix,4,mode)) continue;
43	const Particles & pi0 = chi.decayProducts()[ix].at(111);
44	unsigned int imode = 0;
45	if(chi.decaying()[ix].pid()==20443)    imode=1;
46	else if(chi.decaying()[ix].pid()==445) imode=2;
47	for(unsigned int ix=0;ix<pi0.size();++ix) {
48	  for(unsigned int iy=ix+1;iy<pi0.size();++iy) {
49	    _h[imode]->fill((pi0[ix].momentum()+pi0[iy].momentum()).mass());
50	  }
51	}
52      }
53    }
54
55
56    /// Normalise histograms etc., after the run
57    void finalize() {
58      for(unsigned int ix=0;ix<3;++ix)
59	normalize(_h[ix]);
60    }
61
62    /// @}
63
64
65    /// @name Histograms
66    /// @{
67    Histo1DPtr _h[3];
68    /// @}
69
70
71  };
72
73
74  RIVET_DECLARE_PLUGIN(BESIII_2010_I878544);
75
76}