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BELLE_2021_I1835729

Mass distributions in $\Xi^0_c\to\Xi^0K^+K^-$
Experiment: BELLE (KEKB)
Inspire ID: 1835729
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • Phys.Rev.D 103 (2021) 11, 112002
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing Xic0 mesons

Measurement of the mass distributions in the decay $\Xi^0_c\to\Xi^0K^+K^-$ by BELLE. The data were read from the plots in the paper, and for many points the error bars are the size of the point. It is also not clear that any resolution effects have been unfolded.

Source code: BELLE_2021_I1835729.cc 
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"

namespace Rivet {


  /// @brief Xi_c0 -> Xi0 K+K-
  class BELLE_2021_I1835729 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2021_I1835729);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid==4132);
      declare(ufs, "UFS");
      DecayedParticles XIC0(ufs);
      XIC0.addStable(PID::PI0);
      XIC0.addStable(PID::K0S);
      XIC0.addStable(PID::ETA);
      XIC0.addStable(PID::ETAPRIME);
      XIC0.addStable(PID::XI0);
      declare(XIC0, "XIC0");
      // histograms
      for(unsigned int ix=0;ix<3;++ix)
	book(_h[ix],1,1,1+ix);
      book(_dalitz, "dalitz",50,0.9,1.4,50,3.2,4.);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId,unsigned int> & mode   = { {-321,1},{ 321,1}, { PID::XI0,1}};
      static const map<PdgId,unsigned int> & modeCC = { { 321,1},{-321,1}, {-PID::XI0,1}};
      DecayedParticles XIC0 = apply<DecayedParticles>(event, "XIC0");
      // loop over particles
      for(unsigned int ix=0;ix<XIC0.decaying().size();++ix) {
	int sign = 1;
	if (XIC0.decaying()[ix].pid()>0 && XIC0.modeMatches(ix,3,mode)) {
	  sign=1;
	}
	else if  (XIC0.decaying()[ix].pid()<0 && XIC0.modeMatches(ix,3,modeCC)) {
	  sign=-1;
	}
	else
	  continue;
	const Particles & xi0 = XIC0.decayProducts()[ix].at( sign*PID::XI0);
	const Particles & Kp  = XIC0.decayProducts()[ix].at( sign*PID::KPLUS);
	const Particles & Km  = XIC0.decayProducts()[ix].at( sign*PID::KMINUS);
	double mXiKp = (xi0[0].momentum()+Kp[0].momentum()).mass2();
	double mXiKm = (xi0[0].momentum()+Km[0].momentum()).mass2();
	double mKK   = (Kp [0].momentum()+Km[0].momentum()).mass2();
	_dalitz ->fill(mKK,mXiKm);
	_h[0]->fill(sqrt(mKK  ));
	_h[1]->fill(sqrt(mXiKm));
	_h[2]->fill(sqrt(mXiKp));
      }
    }


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

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[3];
    Histo2DPtr _dalitz;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BELLE_2021_I1835729);

}