Rivet analyses

Mass distributions in χc → π+π−π0π0 and K±π∓KS0π0

Experiment: CLEO (CESR)

Inspire ID: 787608

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 78 (2008) 092004

Beams: * *

Beam energies: ANY

Run details: - Any process producing chi_c states

Measurement of the mass distributions in the decays χc → π+π−π0π0 and K±π∓KS0π0$. The data were read from the plots in the paper and may not be corrected for efficiency.

Source code:CLEO_2008_I787608.cc

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

namespace Rivet {


  /// @briefchi_c -> pi+pi- 2pi0 and K pi K0 pi0
  class CLEO_2008_I787608 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CLEO_2008_I787608);


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

    /// Book histograms and initialise projections before the run
    void init() {
      UnstableParticles ufs = UnstableParticles(Cuts::pid == 10441 or Cuts::pid == 20443 or Cuts::pid == 445);
      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");
      unsigned int iK[3] = {4, 2, 5};
      for (unsigned int ix = 0; ix < 3; ++ix) {
        for (unsigned int iy = 0; iy < iK[ix]; ++iy) {
          // 4 pion
          if (iy < 2) book(_h_pi[ix][iy], 1 + ix, 1, 1 + iy);
          // 2 K 2 pi
          book(_h_K[ix][iy], 4 + ix, 1, 1 + iy);
        }
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode1 = {{211, 1}, {-211, 1}, {111, 2}};
      static const map<PdgId, unsigned int>& mode2 = {{321, 1}, {-211, 1}, {111, 1}, {310, 1}};
      static const map<PdgId, unsigned int>& mode3 = {{-321, 1}, {211, 1}, {111, 1}, {310, 1}};
      DecayedParticles chi = apply<DecayedParticles>(event, "chi");
      for (unsigned int ix = 0; ix < chi.decaying().size(); ++ix) {
        unsigned int iloc = 0;
        int sign = 1;
        if (chi.decaying()[ix].pid() == 20443)
          iloc = 1;
        else if (chi.decaying()[ix].pid() == 445)
          iloc = 2;
        if (chi.modeMatches(ix, 4, mode1)) {
          const Particle& pim = chi.decayProducts()[ix].at(-211)[0];
          const Particle& pip = chi.decayProducts()[ix].at(211)[0];
          const Particles& pi0 = chi.decayProducts()[ix].at(111);
          for (unsigned int ix = 0; ix < 2; ++ix) {
            _h_pi[iloc][0]->fill((pip.momentum() + pi0[ix].momentum()).mass());
            _h_pi[iloc][1]->fill((pim.momentum() + pi0[ix].momentum()).mass());
          }
          continue;
        }
        else if (chi.modeMatches(ix, 4, mode2)) {
          sign = 1;
        }
        else if (chi.modeMatches(ix, 4, mode3)) {
          sign = -1;
        }
        else
          continue;
        const Particle& pim = chi.decayProducts()[ix].at(-sign * 211)[0];
        const Particle& Kp = chi.decayProducts()[ix].at(sign * 321)[0];
        const Particle& pi0 = chi.decayProducts()[ix].at(111)[0];
        const Particle& K0 = chi.decayProducts()[ix].at(310)[0];
        _h_K[iloc][0]->fill((Kp.momentum() + pim.momentum()).mass());
        _h_K[iloc][1]->fill((pim.momentum() + pi0.momentum()).mass());
        if (_h_K[iloc][2]) _h_K[iloc][2]->fill((Kp.momentum() + pi0.momentum()).mass());
        if (_h_K[iloc][3]) _h_K[iloc][3]->fill((K0.momentum() + pim.momentum()).mass());
        if (_h_K[iloc][4]) _h_K[iloc][4]->fill((K0.momentum() + pi0.momentum()).mass());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      unsigned int iK[3] = {4, 2, 5};
      for (unsigned int ix = 0; ix < 3; ++ix) {
        for (unsigned int iy = 0; iy < iK[ix]; ++iy) {
          // 4 pion
          if (iy < 2) normalize(_h_pi[ix][iy], 1., false);
          // 2 K 2 pi
          normalize(_h_K[ix][iy], 1., false);
        }
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_pi[3][2];
    Histo1DPtr _h_K[3][5];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CLEO_2008_I787608);

}