Rivet analyses

χc1, 2 → ΛΛ̄0ϕ decays

Experiment: BESIII (BEPC)

Inspire ID: 2792993

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 110 (2024) 3, 032016 - arXiv: 2405.20638

Beams: * *

Beam energies: ANY

Run details: - Any process producing chi_c1 abd chi_c2, original e+e- -> psi(2S)

Measurements of mass distributions in χc1, 2 → ΛΛ̄0ϕ decays. The data were read from the plots in the paper and may not be corrected for efficiency but are background subtracted.

Source code:BESIII_2024_I2792993.cc

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

namespace Rivet {


  /// @brief  chi_c1,2 -> Lambda Lambdabar0 phi
  class BESIII_2024_I2792993 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2024_I2792993);

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

    /// Book histograms and initialise projections before the run
    void init() {
      UnstableParticles ufs = UnstableParticles(Cuts::pid == 20443 or Cuts::pid == 445);
      declare(ufs, "UFS");
      DecayedParticles chi(ufs);
      chi.addStable(PID::PHI);
      chi.addStable(PID::LAMBDA);
      chi.addStable(-PID::LAMBDA);
      declare(chi, "chi");
      // histos
      for (unsigned int ix = 0; ix < 2; ++ix)
        for (unsigned int iy = 0; iy < 3; ++iy) book(_h[ix][iy], 1 + ix, 1, 1 + iy);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode = {{3122, 1}, {-3122, 1}, {333, 1}};
      DecayedParticles chi = apply<DecayedParticles>(event, "chi");
      for (unsigned int ix = 0; ix < chi.decaying().size(); ++ix) {
        if (!chi.modeMatches(ix, 3, mode)) continue;
        unsigned int imode = chi.decaying()[ix].pid() == 20443 ? 0 : 1;
        const Particle& lam = chi.decayProducts()[ix].at(3122)[0];
        const Particle& lamb = chi.decayProducts()[ix].at(-3122)[0];
        const Particle& phi = chi.decayProducts()[ix].at(333)[0];
        _h[imode][2]->fill((lam.momentum() + lamb.momentum()).mass());
        _h[imode][0]->fill((lam.momentum() + phi.momentum()).mass());
        _h[imode][1]->fill((lamb.momentum() + phi.momentum()).mass());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for (unsigned int ix = 0; ix < 2; ++ix)
        for (unsigned int iy = 0; iy < 3; ++iy) normalize(_h[ix][iy], 1., false);
    }

    /// @}

    /// @name Histograms
    /// @{
    Histo1DPtr _h[2][3];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BESIII_2024_I2792993);

}