Rivet analyses

Dalitz decay of Ds+ → KS0K+π0

Experiment: BESIII ()

Inspire ID: 2070086

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - arXiv: 2204.09614

Beams: * *

Beam energies: ANY

Run details: - Any process producing D_s+ mesons

Measurement of the mass distributions in the decay Ds+ → KS0K+π0 by BES. 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_I2070086.cc

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

namespace Rivet {


  /// @brief D_s+ -> KS0 K+ pi0
  class BESIII_2022_I2070086 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2022_I2070086);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid==431);
      declare(ufs, "UFS");
      DecayedParticles DS(ufs);
      DS.addStable(PID::PI0);
      DS.addStable(PID::K0S);
      declare(DS, "DS");
      // histograms
      book(_h_KK  ,1,1,1);
      book(_h_K0pi,1,1,2);
      book(_h_Kppi,1,1,3);
      book(_dalitz,"dalitz",50,0.3,2.3,50,0.3,2.3);
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId,unsigned int> & mode   = { { 321,1},{ 111,1}, {310,1}};
      static const map<PdgId,unsigned int> & modeCC = { {-321,1},{ 111,1}, {310,1}};
      DecayedParticles DS = apply<DecayedParticles>(event, "DS");
      // loop over particles
      for(unsigned int ix=0;ix<DS.decaying().size();++ix) {
    int sign = 1;
    if (DS.decaying()[ix].pid()>0 && DS.modeMatches(ix,3,mode)) {
      sign=1;
    }
    else if  (DS.decaying()[ix].pid()<0 && DS.modeMatches(ix,3,modeCC)) {
      sign=-1;
    }
    else
      continue;
    const Particle & K0  = DS.decayProducts()[ix].at(      310)[0];
    const Particle & pi0 = DS.decayProducts()[ix].at(      111)[0];
    const Particle & Kp  = DS.decayProducts()[ix].at( sign*321)[0];
    double m0  = (K0.momentum()+pi0.momentum()).mass2();
    double mp  = (Kp.momentum()+pi0.momentum()).mass2();
    double mKK = (K0.momentum()+Kp.momentum()).mass2();
    _dalitz->fill(mp,m0);
    _h_KK->fill(sqrt(mKK));
    _h_Kppi->fill(sqrt(mp));
    _h_K0pi->fill(sqrt(m0));
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_K0pi);
      normalize(_h_Kppi);
      normalize(_h_KK  );
      normalize(_dalitz);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_K0pi,_h_Kppi,_h_KK;
    Histo2DPtr _dalitz;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BESIII_2022_I2070086);

}