Rivet analyses

χ_c1 → η^(′)π⁺π⁻

Experiment: CLEOC (CESR)

Inspire ID: 929693

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 84 (2011) 112009

Beams: * *

Beam energies: ANY

Run details: none listed

Measurement of the mass distributions in the decays χ_c1 → η^(′)π⁺π⁻. The data were read from the plots in the paper and may not be corrected for efficiency.

Source code:`CLEOC_2011_I929693.cc`

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"

namespace Rivet {


  /// @brief chi_c1 -> eta(') pi+-pi
  class CLEOC_2011_I929693 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOC_2011_I929693);


    /// @name Analysis methods
    /// @{

    /// Book histograms and initialise projections before the run
    void init() {
      UnstableParticles ufs = UnstableParticles(Cuts::pid==20443);
      declare(ufs, "UFS");
      DecayedParticles chi(ufs);
      chi.addStable( PID::PI0);
      chi.addStable( PID::K0S);
      chi.addStable( PID::ETA);
      chi.addStable( PID::ETAPRIME);
      declare(chi, "chi");
      for(unsigned int ix=0;ix<2;++ix)
    for(unsigned int iy=0;iy<2;++iy)
      book(_h[ix][iy],ix+1,1,iy+1);
      book(_dalitz[0],"dalitz_1",50,0.,12.,50,0., 9.);
      book(_dalitz[1],"dalitz_2",50,0.,12.,50,0., 7.);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId,unsigned int> & mode1 = { { 221,1}, { 211,1}, {-211,1} };
      static const map<PdgId,unsigned int> & mode2 = { { 331,1}, { 211,1}, {-211,1} };
      DecayedParticles chi = apply<DecayedParticles>(event, "chi");
      // loop over particles
      for(unsigned int ix=0;ix<chi.decaying().size();++ix) {
    if(chi.modeMatches(ix,3,mode1)) {
      const Particle & eta = chi.decayProducts()[ix].at( 221)[0];
      const Particle & pim = chi.decayProducts()[ix].at(-211)[0];
      const Particle & pip = chi.decayProducts()[ix].at( 211)[0];
      double m1 = (pip.momentum()+pim.momentum()).mass2();
      double m2 = (eta.momentum()+pip.momentum()).mass2();
      double m3 = (eta.momentum()+pim.momentum()).mass2();
      _dalitz[0]->fill(m2,m1);
      _h[0][1]->fill(sqrt(m1));
      _h[0][0]->fill(sqrt(m2));
      _h[0][0]->fill(sqrt(m3));
    }
    else if(chi.modeMatches(ix,3,mode2)) {
      const Particle & eta = chi.decayProducts()[ix].at( 331)[0];
      const Particle & pim = chi.decayProducts()[ix].at(-211)[0];
      const Particle & pip = chi.decayProducts()[ix].at( 211)[0];
      double m1 = (pip.momentum()+pim.momentum()).mass2();
      double m2 = (eta.momentum()+pip.momentum()).mass2();
      double m3 = (eta.momentum()+pim.momentum()).mass2();
      _dalitz[1]->fill(m2,m1);
      _h[1][1]->fill(sqrt(m1));
      _h[1][0]->fill(sqrt(m2));
      _h[1][0]->fill(sqrt(m3));
    }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for(unsigned int ix=0;ix<2;++ix) {
    normalize(_dalitz[ix]);
    for(unsigned int iy=0;iy<2;++iy)
      normalize(_h[ix][iy]);
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[2][2];
    Histo2DPtr _dalitz[2];
    /// @}


  };


  RIVET_DECLARE_PLUGIN(CLEOC_2011_I929693);

}

Rivet analyses

χc1 → η(′)π+π−

Source code:CLEOC_2011_I929693.cc

χ_c1 → η^(′)π⁺π⁻

Source code:`CLEOC_2011_I929693.cc`