Rivet analyses

Mass distributions in the decays B0 → Ds−KS0π+ and B+ → Ds−K+K+

Experiment: BELLE (KEKB)

Inspire ID: 1326905

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 91 (2015) 3, 032008

Beams: * *

Beam energies: ANY

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

Mass distributions in the decays B0 → Ds−KS0π+ and B+ → Ds−K+K+, the data were read from the plots in the paper and although the backgrounds have been subtracted they may be be correct for efficiency.

Source code:BELLE_2015_I1326905.cc

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

namespace Rivet {


  /// @brief B0 ->\to Ds- KS0 pi+ and B+ -> Ds- K+ K^+
  class BELLE_2015_I1326905 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2015_I1326905);


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

    /// Book histograms and initialise projections before the run
    void init() {
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511 or Cuts::abspid == 521);
      declare(ufs, "UFS");
      DecayedParticles BB(ufs);
      BB.addStable(431);
      BB.addStable(-431);
      BB.addStable(310);
      declare(BB, "BB");
      //histograms
      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) {
      static const map<PdgId, unsigned int>& mode1 = {{-431, 1}, {310, 1}, {211, 1}};
      static const map<PdgId, unsigned int>& mode1CC = {{431, 1}, {310, 1}, {-211, 1}};
      static const map<PdgId, unsigned int>& mode2 = {{-431, 1}, {321, 2}};
      static const map<PdgId, unsigned int>& mode2CC = {{431, 1}, {-321, 2}};
      DecayedParticles BB = apply<DecayedParticles>(event, "BB");
      for (unsigned int ix = 0; ix < BB.decaying().size(); ++ix) {
        int sign = 1, imode = 0;
        if (BB.decaying()[ix].pid() > 0 && BB.modeMatches(ix, 3, mode1)) {
          imode = 0;
          sign = 1;
        }
        else if (BB.decaying()[ix].pid() < 0 && BB.modeMatches(ix, 3, mode1CC)) {
          imode = 0;
          sign = -1;
        }
        else if (BB.decaying()[ix].pid() > 0 && BB.modeMatches(ix, 3, mode2)) {
          imode = 1;
          sign = 1;
        }
        else if (BB.decaying()[ix].pid() < 0 && BB.modeMatches(ix, 3, mode2CC)) {
          imode = 1;
          sign = -1;
        }
        else
          continue;
        const Particle& Ds = BB.decayProducts()[ix].at(-sign * 431)[0];
        FourMomentum pK;
        if (imode == 0) {
          pK = BB.decayProducts()[ix].at(310)[0].momentum();
        }
        else {
          const Particles& Kp = BB.decayProducts()[ix].at(sign * 321);
          pK = Kp[0].momentum().p3().mod() > Kp[1].momentum().p3().mod() ? Kp[1].momentum()
                                                                         : Kp[0].momentum();
        }
        _h[imode]->fill((Ds.momentum() + pK).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(BELLE_2015_I1326905);

}