Rivet analyses

B̄0 → KS0K∓π±

Experiment: BELLE (KEKB)

Inspire ID: 1729723

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 100 (2019) 1, 011101

Beams: * *

Beam energies: ANY

Run details: - Any process producing B0 originally e+e- at Upsilon(4S)

Measurement of the mass distributions in the decays B̄0 → KS0K∓π±. The data were read from the plots in the paper, but is corrected for detector efficiency.

Source code:BELLE_2019_I1729723.cc

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

namespace Rivet {


  /// @brief B0 -> KS0 K-+ pi+-
  class BELLE_2019_I1729723 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2019_I1729723);


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

    /// Book histograms and initialise projections before the run
    void init() {
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511);
      declare(ufs, "UFS");
      DecayedParticles B0(ufs);
      B0.addStable(PID::PI0);
      B0.addStable(PID::K0S);
      B0.addStable(PID::ETA);
      B0.addStable(PID::ETAPRIME);
      declare(B0, "B0");
      for (unsigned int ix = 0; ix < 3; ++ix) {
        for (unsigned int iy = 0; iy < 2; ++iy) {
          book(_h[ix][iy], 1 + ix, 1, 1 + iy);
        }
      }
      book(_n, "TMP/nB0");
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode = {{310, 1}, {-321, 1}, {211, 1}};
      static const map<PdgId, unsigned int>& modeCC = {{310, 1}, {321, 1}, {-211, 1}};
      DecayedParticles B0 = apply<DecayedParticles>(event, "B0");
      // loop over particles
      for (unsigned int ix = 0; ix < B0.decaying().size(); ++ix) {
        _n->fill();
        unsigned int iloc(0);
        int sign = 1;
        if (B0.modeMatches(ix, 3, mode)) {
          sign = 1;
          iloc = B0.decaying()[ix].pid() > 0 ? 1 : 0;
        }
        else if (B0.modeMatches(ix, 3, modeCC)) {
          sign = -1;
          iloc = B0.decaying()[ix].pid() > 0 ? 0 : 1;
        }
        else
          continue;
        const Particle& pip = B0.decayProducts()[ix].at(sign * 211)[0];
        const Particle& Km = B0.decayProducts()[ix].at(-sign * 321)[0];
        const Particle& K0 = B0.decayProducts()[ix].at(310)[0];
        _h[0][iloc]->fill((Km.momentum() + pip.momentum()).mass());
        _h[1][iloc]->fill((K0.momentum() + pip.momentum()).mass());
        _h[2][iloc]->fill((Km.momentum() + K0.momentum()).mass());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for (unsigned int ix = 0; ix < 3; ++ix) {
        for (unsigned int iy = 0; iy < 2; ++iy) {
          scale(_h[ix][iy], 1e7 / *_n);
        }
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[3][2];
    CounterPtr _n;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BELLE_2019_I1729723);

}