Rivet analyses

Dalitz decay of D⁺ and D_s⁺ → K⁺π⁺π⁻

Experiment: FOCUS (Fermilab)

Inspire ID: 654030

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Lett.B 601 (2004) 10-19

Beams: * *

Beam energies: ANY

Run details: - Any process producing D+ or D_s+ mesons

Measurement of the mass distributions in the decays D⁺ and D_s⁺ → K⁺π⁺π⁻ 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_2004_I654030.cc`

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

namespace Rivet {


  /// @brief D+/Ds+ -> K+ pi+ pi-
  class FOCUS_2004_I654030 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(FOCUS_2004_I654030);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid==411 or
                        Cuts::abspid==431);
      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_Kpim[ix],1+ix,1,1);
    book(_h_pipi[ix],1+ix,1,2);
    book(_dalitz[ix],"dalitz_"+to_str(ix+1),50,0.3,3.5,50,0.,2.3);
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId,unsigned int> & mode   = { { 211,1}, { 321,1}, {-211,1}};
      static const map<PdgId,unsigned int> & modeCC = { {-211,1}, {-321,1}, { 211,1}};
      DecayedParticles DD = apply<DecayedParticles>(event, "DD");
      // loop over particles
      for(unsigned int ix=0;ix<DD.decaying().size();++ix) {
    int sign = 1;
    if (DD.decaying()[ix].pid()>0 && DD.modeMatches(ix,3,mode)) {
      sign=1;
    }
    else if  (DD.decaying()[ix].pid()<0 && DD.modeMatches(ix,3,modeCC)) {
      sign=-1;
    }
    else
      continue;
    const Particle & Kp  = DD.decayProducts()[ix].at( sign*321)[0];
    const Particle & pip = DD.decayProducts()[ix].at( sign*211)[0];
    const Particle & pim = DD.decayProducts()[ix].at(-sign*211)[0];
    double mm    = (Kp .momentum()+pim.momentum()).mass2();
    double mpipi = (pip.momentum()+pim.momentum()).mass2();
    unsigned int iloc = DD.decaying()[ix].abspid()==411 ? 0 : 1;
    _dalitz[iloc]->fill(mm,mpipi);
    _h_pipi[iloc]->fill(mpipi);
    _h_Kpim[iloc]->fill(mm);
      }
    }


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

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_Kpim[2],_h_pipi[2];
    Histo2DPtr _dalitz[2];
    /// @}


  };


  RIVET_DECLARE_PLUGIN(FOCUS_2004_I654030);

}

Rivet analyses

Dalitz decay of D+ and Ds+ → K+π+π−

Source code:FOCUS_2004_I654030.cc

Dalitz decay of D⁺ and D_s⁺ → K⁺π⁺π⁻

Source code:`FOCUS_2004_I654030.cc`