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FOCUS_2003_I626320

Mass distributions in the $D^0\to K^-K^-K^+\pi^+$
Experiment: FOCUS (Fermilab)
Inspire ID: 626320
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • Phys.Lett.B 575 (2003) 190-197
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing D_s+ mesons

Measurement of the mass distributions in the decay $D^0\to K^-K^-K^+\pi^+$ by FOCUS. 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: FOCUS_2003_I626320.cc 
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"

namespace Rivet {


  /// @brief D0 -> K-K+K-pi+
  class FOCUS_2003_I626320 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(FOCUS_2003_I626320);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid==421);
      declare(ufs, "UFS");
      DecayedParticles D0(ufs);
      D0.addStable(PID::PI0);
      D0.addStable(PID::K0S);
      D0.addStable(PID::ETA);
      D0.addStable(PID::ETAPRIME);
      declare(D0, "D0");
      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) {
      // define the decay mode
      static const map<PdgId,unsigned int> & mode   = { { 321,1}, {-321,2},{ 211,1}};
      static const map<PdgId,unsigned int> & modeCC = { {-321,1}, { 321,2},{-211,1}};
      DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
      // loop over particles
      for(unsigned int ix=0;ix<D0.decaying().size();++ix) {
	int sign = 1;
	if (D0.decaying()[ix].pid()>0 && D0.modeMatches(ix,4,mode)) {
	  sign=1;
	}
	else if  (D0.decaying()[ix].pid()<0 && D0.modeMatches(ix,4,modeCC)) {
	  sign=-1;
	}
	else
	  continue;
	const Particles & Kp = D0.decayProducts()[ix].at( sign*321);
	const Particles & Km = D0.decayProducts()[ix].at(-sign*321);
	const Particles & pip= D0.decayProducts()[ix].at( sign*211);
	_h[0]->fill((Kp [0].momentum()+Km [0].momentum()).mass());
	_h[0]->fill((Kp [0].momentum()+Km [1].momentum()).mass());
	_h[1]->fill((Km [0].momentum()+pip[0].momentum()).mass());
	_h[1]->fill((Km [1].momentum()+pip[0].momentum()).mass());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for(unsigned int ix=0;ix<2;++ix)
	normalize(_h[ix],1.,false);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[2];
    /// @}


  };


  RIVET_DECLARE_PLUGIN(FOCUS_2003_I626320);

}