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/DecayedParticles.hh"
#include "Rivet/Projections/UnstableParticles.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);

}