rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

BESIII_2012_I1128258

Mass distributions in $\chi_{cJ}\to p\bar{n}\pi^-$ and $p\bar{n}\pi^-\pi^0$
Experiment: BESIII (BEPC)
Inspire ID: 1128258
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • Phys.Rev.D 86 (2012) 052011
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing chi_c0,1,2

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

Source code: BESIII_2012_I1128258.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_c -> p nbar pi- p nbar pi- pi0
 10  class BESIII_2012_I1128258 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2012_I1128258);
 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==20444);
 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      book(_h[3],2,1,1);
 34    }
 35
 36
 37    /// Perform the per-event analysis
 38    void analyze(const Event& event) {
 39      static const map<PdgId,unsigned int> & mode1   = { { 2212,1}, {-2112,1}, {-211,1}};
 40      static const map<PdgId,unsigned int> & mode1CC = { {-2212,1}, { 2112,1}, { 211,1}};
 41      static const map<PdgId,unsigned int> & mode2   = { { 2212,1}, {-2112,1}, {-211,1}, {111,1}};
 42      static const map<PdgId,unsigned int> & mode2CC = { {-2212,1}, { 2112,1}, { 211,1}, {111,1}};
 43      DecayedParticles chi = apply<DecayedParticles>(event, "chi");
 44      // loop over particles
 45      for(unsigned int ix=0;ix<chi.decaying().size();++ix) {
 46      	int mode=-1,sign=0;
 47      	if (chi.decaying()[ix].pid()==10441) {
 48      	  if(chi.modeMatches(ix,3,mode1)) {
 49      	    mode=0;
 50      	    sign=1;
 51      	  }
 52      	  else if(chi.modeMatches(ix,3,mode1CC)) {
 53      	    mode= 0;
 54      	    sign=-1;
 55      	  }
 56	
 57
 58       	}
 59      	if(mode==0) {
 60      	  const Particle & pim  = chi.decayProducts()[ix].at( -211*sign)[0];
 61      	  const Particle & pp   = chi.decayProducts()[ix].at( 2212*sign)[0];
 62      	  const Particle & nbar = chi.decayProducts()[ix].at(-2112*sign)[0];
 63      	  _h[0]->fill((pp  .momentum()+pim .momentum()).mass());
 64      	  _h[1]->fill((nbar.momentum()+pim .momentum()).mass());
 65      	  _h[2]->fill((pp  .momentum()+nbar.momentum()).mass());
 66	  continue;
 67      	}
 68      	else if(chi.modeMatches(ix,4,mode2)) {
 69      	  mode=1;
 70      	  sign=1;
 71      	}
 72      	else if(chi.modeMatches(ix,4,mode2CC)) {
 73      	  mode= 1;
 74      	  sign=-1;
 75      	}
 76      	else
 77      	  continue;
 78      	const Particle & pim = chi.decayProducts()[ix].at( -211*sign)[0];
 79      	const Particle & pi0 = chi.decayProducts()[ix].at(  111     )[0];
 80      	_h[3]->fill((pim.momentum()+pi0.momentum()).mass());
 81      }
 82    }
 83
 84
 85    /// Normalise histograms etc., after the run
 86    void finalize() {
 87      for(unsigned int ix=0;ix<4;++ix)
 88	normalize(_h[ix]);
 89    }
 90
 91    /// @}
 92
 93
 94    /// @name Histograms
 95    /// @{
 96    Histo1DPtr _h[4];
 97    /// @}
 98
 99
100  };
101
102
103  RIVET_DECLARE_PLUGIN(BESIII_2012_I1128258);
104
105}