Rivet analyses

Mass distributions in B⁺ → J/ψ, ψ(2S) + K⁺π⁺π⁻

Experiment: BELLE (KEKB)

Inspire ID: 871475

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 83 (2011) 032005

Beams: * *

Beam energies: ANY

Run details: - Any process producing B+ mesons, originally Upsilon(4S) decays

Measurement of mass distributions in the decays B⁺ → J/ψ, ψ(2S) + K⁺π⁺π⁻. The data were read from the plots in the paper and may not have been corrected for efficiency and resolution, although ther backgrounds given in the paper have been subtracted.

Source code:`BELLE_2010_I871475.cc`

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

namespace Rivet {


  /// @brief B+ -> J/psi/psi(2S) K+ pi+ pi-
  class BELLE_2010_I871475 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2010_I871475);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid==521);
      declare(ufs, "UFS");
      DecayedParticles BP(ufs);
      BP.addStable(100443);
      BP.addStable(443);
      declare(BP, "BP");
      // histograms
      vector<double> bins[2] = {{0.60,1.46,2.32,3.18,4.04,4.90},
                                {0.60,1.00,1.40,1.80,2.20,2.60}};
      for (size_t ix=0; ix<2; ++ix) {
        book(_c[ix],"TMP/c_"+toString(ix+1));
        for (size_t iy=0; iy<3; ++iy) {
          book(_h_all[ix][iy], 1+ix, 1, 1+iy);
          if (iy>1) continue;
          book(_h_slice[ix][iy], bins[ix]);
          for (auto& b : _h_slice[ix][iy]->bins()) {
            book(b, 3+ix, 1+iy, b.index());
          }
        }
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId,unsigned int> & mode1   = { { 321,1}, { 211,1}, {-211,1}, {    443,1}};
      static const map<PdgId,unsigned int> & mode1CC = { {-321,1}, { 211,1}, {-211,1}, {    443,1}};
      static const map<PdgId,unsigned int> & mode2   = { { 321,1}, { 211,1}, {-211,1}, { 100443,1}};
      static const map<PdgId,unsigned int> & mode2CC = { {-321,1}, { 211,1}, {-211,1}, { 100443,1}};
      DecayedParticles BP = apply<DecayedParticles>(event, "BP");
      // loop over particles
      for (unsigned int ix=0;ix<BP.decaying().size();++ix) {
        int imode=-1, sign = 1;
        if (BP.decaying()[ix].pid()>0 && BP.modeMatches(ix,4,mode1)) {
          sign=1;
          imode=0;
        }
        else if  (BP.decaying()[ix].pid()<0 && BP.modeMatches(ix,4,mode1CC)) {
          sign=-1;
          imode=0;
        }
        else if (BP.decaying()[ix].pid()>0 && BP.modeMatches(ix,4,mode2)) {
          sign=1;
          imode=1;
        }
        else if  (BP.decaying()[ix].pid()<0 && BP.modeMatches(ix,4,mode2CC)) {
          sign=-1;
          imode=1;
        }
        else {
          continue;
        }
        const Particle& Kp  = BP.decayProducts()[ix].at( 321*sign)[0];
        const Particle& pip = BP.decayProducts()[ix].at( 211*sign)[0];
        const Particle& pim = BP.decayProducts()[ix].at(-211*sign)[0];
        double m2Kpipi = (Kp .momentum()+pip.momentum()+pim.momentum()).mass2();
        double m2Kpi   = (Kp .momentum()+pim.momentum()).mass2();
        double m2pipi  = (pip.momentum()+pim.momentum()).mass2();
        _h_all[imode][0]->fill(m2Kpipi);
        _h_all[imode][1]->fill(m2Kpi  );
        _h_all[imode][2]->fill(m2pipi );
        _h_slice[imode][0]->fill(m2Kpipi, m2Kpi );
        _h_slice[imode][1]->fill(m2Kpipi, m2pipi);
        _c[imode]->fill();
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for (size_t ix=0; ix<2; ++ix) {
        for (size_t iy=0; iy<3; ++iy) {
          scale(_h_all[ix][iy], 1./ *_c[ix]);
          if(iy>1) continue;
          scale(_h_slice[ix][iy], 1./ *_c[ix]);
        }
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_all[2][3];
    Histo1DGroupPtr _h_slice[2][2];
    CounterPtr _c[2];
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BELLE_2010_I871475);

}

Rivet analyses

Mass distributions in B+ → J/ψ, ψ(2S) + K+π+π−

Source code:BELLE_2010_I871475.cc

Mass distributions in B⁺ → J/ψ, ψ(2S) + K⁺π⁺π⁻

Source code:`BELLE_2010_I871475.cc`