Rivet analyses

Mass distributions in D+ → KS0KS0π+ decays

Experiment: BESIII (BEPC)

Inspire ID: 2824162

Status: VALIDATED NOHEPDAT

Authors: - Peter Richardson

References: - Phys.Rev.D 110 (2024) 9, 092006 - arXiv: 2409.01419

Beams: * *

Beam energies: ANY

Run details: - Any process producting D+ mesons, originally psi(3770) decay

Measurement of the mass distributions in D+ → KS0KS0π+π0 decays by the BESIII collaboration. The data were read from the plots in the paper, and then the backgrounds given subtracted. Resolution and efficiencies have not been unfolded.

Source code:BESIII_2024_I2824162.cc

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

namespace Rivet {


  /// @brief Add a short analysis description here
  class BESIII_2024_I2824162 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2024_I2824162);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 411);
      declare(ufs, "UFS");
      DecayedParticles DD(ufs);
      DD.addStable(PID::PI0);
      DD.addStable(PID::K0S);
      declare(DD, "DD");
      // histograms
      for (unsigned int ix = 0; ix < 2; ++ix) {
        book(_h[ix], 1, 1, 1 + ix);
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      DecayedParticles DD = apply<DecayedParticles>(event, "DD");
      // loop over particles
      for (unsigned int ix = 0; ix < DD.decaying().size(); ++ix) {
        int sign = DD.decaying()[ix].pid() / DD.decaying()[ix].abspid();
        if (!DD.modeMatches(ix, 3, mode) && !DD.modeMatches(ix, 3, modeCC)) continue;
        const Particles& K0S = DD.decayProducts()[ix].at(PID::K0S);
        const Particle& pip = DD.decayProducts()[ix].at(sign * 211)[0];
        _h[0]->fill((K0S[0].mom() + K0S[1].mom()).mass2());
        _h[1]->fill((K0S[0].mom() + pip.mom()).mass2());
        _h[1]->fill((K0S[1].mom() + pip.mom()).mass2());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[2];
    const map<PdgId, unsigned int> mode = {{PID::K0S, 2}, {211, 1}};
    const map<PdgId, unsigned int> modeCC = {{PID::K0S, 2}, {-211, 1}};
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BESIII_2024_I2824162);

}