Rivet analyses

Mass distributions in D0 → KS0π+π0π0 decays

Experiment: BESIII (BEPC)

Inspire ID: 2088337

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - arXiv: 2205.14031

Beams: * *

Beam energies: ANY

Run details: none listed

Measurement of the mass distributions in D0 → KS0π+π0π0 decays by the BESIII collaboration. The data were read from the plots in the paper and therefore for some points the error bars are the size of the point. It is also not clear that any resolution effects have been unfolded.

Source code:BESIII_2022_I2088337.cc

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

namespace Rivet {


  /// @brief D0 -> KS0 pi+ pi0 pi0
  class BESIII_2022_I2088337 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2022_I2088337);


    /// @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<7;++ix) {
    book(_h[ix],1,1,1+ix);
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId,unsigned int> & mode   = { {310,1}, { 211,1}, { 111,2} };
      static const map<PdgId,unsigned int> & modeCC = { {310,1}, {-211,1}, { 111,2} };
      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,4,mode) && !DD.modeMatches(ix,4,modeCC)) continue;
    const Particles & KS0 = DD.decayProducts()[ix].at(      310);
    const Particles & pip = DD.decayProducts()[ix].at( sign*211);
    const Particles & pi0 = DD.decayProducts()[ix].at(      111);
    _h[0]->fill((pi0[0].momentum()+pi0[1].momentum()).mass());
    _h[3]->fill((KS0[0].momentum()+pip[0].momentum()).mass());
    _h[5]->fill((KS0[0].momentum()+pi0[0].momentum()+pi0[1].momentum()).mass());
    _h[6]->fill((pip[0].momentum()+pi0[0].momentum()+pi0[1].momentum()).mass());
    for(unsigned int ix=0;ix<2;++ix) {
      _h[1]->fill((KS0[0].momentum()+pi0[ix].momentum()).mass());
      _h[2]->fill((pip[0].momentum()+pi0[ix].momentum()).mass());
      _h[4]->fill((KS0[0].momentum()+pip[0].momentum()+pi0[ix].momentum()).mass());
    }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for(unsigned int ix=0;ix<7;++ix) {
    normalize(_h[ix]);
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[7];
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BESIII_2022_I2088337);

}