Rivet analyses

ψ(2S) → Λ0Σ̄±π∓ + c.c.

Experiment: BESIII (BEPC)

Inspire ID: 1261765

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 88 (2013) 11, 112007

Beams: * *

Beam energies: ANY

Run details: - Any process producing psi(2S), originally e+e-

Measurements of mass distributions in the decays ψ(2S) → Λ0Σ̄±π∓ +c.c.. The data were read from the plots in the paper and may not be corrected for efficiency but the background given in the paper have been subtracted.

Source code:BESIII_2013_I1261765.cc

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

namespace Rivet {


  /// @brief psi(2S) -> Lambda Sigmabar+- pi-+
  class BESIII_2013_I1261765 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2013_I1261765);


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

    /// Book histograms and initialise projections before the run
    void init() {
      UnstableParticles ufs = UnstableParticles(Cuts::pid==100443);
      declare(ufs, "UFS");
      DecayedParticles psi(ufs);
      psi.addStable( PID::PI0);
      psi.addStable( PID::K0S);
      psi.addStable( PID::SIGMAPLUS);
      psi.addStable( PID::SIGMAMINUS);
      psi.addStable(-PID::SIGMAPLUS);
      psi.addStable(-PID::SIGMAMINUS);
      psi.addStable( PID::LAMBDA);
      psi.addStable(-PID::LAMBDA);
      declare(psi, "psi");
      for(unsigned int ix=0;ix<3;++ix)
    book(_h[ix],1,1,1+ix);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId,unsigned int> & mode1   = { { 3122,1}, {-3222,1}, { 211,1} };
      static const map<PdgId,unsigned int> & mode1CC = { {-3122,1}, { 3222,1}, {-211,1} };
      static const map<PdgId,unsigned int> & mode2   = { { 3122,1}, {-3112,1}, {-211,1} };
      static const map<PdgId,unsigned int> & mode2CC = { {-3122,1}, { 3112,1}, { 211,1} };
      DecayedParticles psi = apply<DecayedParticles>(event, "psi");
      for(unsigned int ix=0;ix<psi.decaying().size();++ix) {
    int ipi=211, isigma=-3222,sign=1;
    if(psi.modeMatches(ix,3,mode1)) {
      sign =  1;
    }
    else if(psi.modeMatches(ix,3,mode1CC)) {
      sign = -1;
    }
    else if(psi.modeMatches(ix,3,mode2)) {
      ipi=-211;
      isigma=-3112;
      sign =  1;
    }
    else if(psi.modeMatches(ix,3,mode2CC)) {
      ipi=-211;
      isigma=-3112;
      sign = -1;
    } 
    else
      continue;
    const Particle & lam   = psi.decayProducts()[ix].at( sign*3122  )[0];
    const Particle & pim   = psi.decayProducts()[ix].at( sign*ipi   )[0];
    const Particle & sigma = psi.decayProducts()[ix].at( sign*isigma)[0];
    _h[0]->fill((lam.momentum()+pim  .momentum()).mass());
    _h[1]->fill((pim.momentum()+sigma.momentum()).mass());
    _h[2]->fill((lam.momentum()+sigma.momentum()).mass());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for(unsigned int ix=0;ix<3;++ix)
    normalize(_h[ix],1.,false);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[3];
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BESIII_2013_I1261765);

}