Rivet analyses

Mass distributions in B0 → K+K−KS0

Experiment: BELLE (KEKB)

Inspire ID: 862241

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 82 (2010) 073011

Beams: * *

Beam energies: ANY

Run details: - Any process producing B0 mesons, originally Upsilon(4S) decays

Measurement of Mass distributions in B0 → K+K−KS0 decays. The data were read from the plots in the paper and may not be corrected for efficiency/acceptable, however the backgrounds given in the paper have been subtracted.

Source code:BELLE_2010_I862241.cc

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

namespace Rivet {


  /// @brief B0 -> K+ K- KS0
  class BELLE_2010_I862241 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2010_I862241);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511);
      declare(ufs, "UFS");
      DecayedParticles B0(ufs);
      B0.addStable(PID::K0S);
      declare(B0, "B0");
      // histograms
      for (unsigned int ix = 0; ix < 4; ++ix) book(_h[ix], 1, 1, 1 + ix);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode = {{321, 1}, {-321, 1}, {310, 1}};
      DecayedParticles B0 = apply<DecayedParticles>(event, "B0");
      // loop over particles
      for (unsigned int ix = 0; ix < B0.decaying().size(); ++ix) {
        if (!B0.modeMatches(ix, 3, mode)) continue;
        int sign = B0.decaying()[ix].pid() > 0 ? 1 : -1;
        const Particle& Kp = B0.decayProducts()[ix].at(321 * sign)[0];
        const Particle& Km = B0.decayProducts()[ix].at(-321 * sign)[0];
        const Particle& K0 = B0.decayProducts()[ix].at(310)[0];
        _h[0]->fill((K0.momentum() + Kp.momentum()).mass());
        _h[1]->fill((K0.momentum() + Km.momentum()).mass());
        _h[2]->fill((Km.momentum() + Kp.momentum()).mass());
        _h[3]->fill((Km.momentum() + Kp.momentum()).mass());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for (unsigned int ix = 0; ix < 4; ++ix) normalize(_h[ix], 1.);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[4];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BELLE_2010_I862241);

}