Rivet analyses

ϕK mass distribution in B+, 0 → ϕK+, 0γ decays

Experiment: BELLE (KEKB)

Inspire ID: 897683

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 84 (2011) 071101

Beams: * *

Beam energies: ANY

Run details: - Any process producing B+ and B0 mesons

Measurement of the ϕK mass distribution in B+, 0 → ϕK+, 0γ decays. The data was read from the plots in the paper whcih are background subtracted and efficiency corrected.

Source code:BELLE_2011_I897683.cc

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

namespace Rivet {


  /// @brief B -> phi K gamma
  class BELLE_2011_I897683 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2011_I897683);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511 || Cuts::abspid == 521);
      declare(ufs, "UFS");
      DecayedParticles BB(ufs);
      BB.addStable(PID::PHI);
      BB.addStable(PID::K0S);
      declare(BB, "BB");
      // histos
      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) {
      DecayedParticles BB = apply<DecayedParticles>(event, "BB");
      // loop over particles
      for (unsigned int ix = 0; ix < BB.decaying().size(); ++ix) {
        int sign = 1, imode = 0, iK = 321;
        if (BB.decaying()[ix].abspid() == 521) {
          if (BB.decaying()[ix].pid() > 0 && BB.modeMatches(ix, 3, mode1)) {
            sign = 1;
          }
          else if (BB.decaying()[ix].pid() < 0 && BB.modeMatches(ix, 3, mode1CC)) {
            sign = -1;
          }
          else {
            continue;
          }
        }
        else if (BB.modeMatches(ix, 3, mode2)) {
          imode = 1;
          iK = 310;
        }
        else {
          continue;
        }
        const Particle& K = BB.decayProducts()[ix].at(sign * iK)[0];
        const Particle& phi = BB.decayProducts()[ix].at(333)[0];
        _h[imode]->fill((K.mom() + phi.mom()).mass());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h, 1., false);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[2];
    const map<PdgId, unsigned int> mode1 = {{333, 1}, {321, 1}, {22, 1}};
    const map<PdgId, unsigned int> mode1CC = {{333, 1}, {-321, 1}, {22, 1}};
    const map<PdgId, unsigned int> mode2 = {{333, 1}, {310, 1}, {22, 1}};
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BELLE_2011_I897683);

}