Rivet analyses

Mass distributions in D⁰ → π⁺π⁻η and D⁰ → K⁺K⁻η

Experiment: BELLE (KEKB)

Inspire ID: 1867474

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - JHEP 09 (2021) 075

Beams: * *

Beam energies: ANY

Run details: - Any process producing D0 mesons

Measurement of the mass distributions in the decays D⁰ → π⁺π⁻η and D⁰ → K⁺K⁻η by BELLE. The data were read from the plots in the paper, and for many points the error bars are the size of the point. It is also not clear that any resolution effects have been unfolded.

Source code:`BELLE_2021_I1867474.cc`

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

namespace Rivet {


  /// @brief D0 -> pi+pi-eta, K+K-eta
  class BELLE_2021_I1867474 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2021_I1867474);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid==421);
      declare(ufs, "UFS");
      DecayedParticles D0(ufs);
      D0.addStable(PID::PI0);
      D0.addStable(PID::K0S);
      D0.addStable(PID::ETA);
      D0.addStable(PID::ETAPRIME);
      declare(D0, "D0");
      // histograms
      for (unsigned int ix=0; ix<2; ++ix) {
        for (unsigned int iy=0; iy<3; ++iy) {
          book(_h[ix][iy],1+ix,1,1+iy);
        }
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
      // loop over particles
      for (unsigned int ix=0; ix<D0.decaying().size(); ++ix) {
        unsigned int imode=0;
        if       (D0.modeMatches(ix,3,mode1)) imode=0;
        else if  (D0.modeMatches(ix,3,mode2)) imode=1;
        else continue;
        int sign = D0.decaying()[ix].pid()/D0.decaying()[ix].abspid();
        int im = 211+imode*110;
        const Particle& eta = D0.decayProducts()[ix].at(221)[0];
        const Particle& pim = D0.decayProducts()[ix].at(-sign*im)[0];
        const Particle& pip = D0.decayProducts()[ix].at( sign*im)[0];
        _h[imode][0]->fill((pip.mom()+pim.mom()).mass2());
        _h[imode][1]->fill((pim.mom()+eta.mom()).mass2());
        _h[imode][2]->fill((pip.mom()+eta.mom()).mass2());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for (unsigned int ix=0; ix<2; ++ix) {
        normalize(_h[ix], 1.0, false);
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[2][3];
    const map<PdgId,unsigned int> mode1 = { { 211,1},{-211,1}, {221,1}};
    const map<PdgId,unsigned int> mode2 = { { 321,1},{-321,1}, {221,1}};
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BELLE_2021_I1867474);

}

Rivet analyses

Mass distributions in D0 → π+π−η and D0 → K+K−η

Source code:BELLE_2021_I1867474.cc

Mass distributions in D⁰ → π⁺π⁻η and D⁰ → K⁺K⁻η

Source code:`BELLE_2021_I1867474.cc`