Rivet analyses

Ds+ → K0e+νe q2 spectrum

Experiment: BESIII (BEPC)

Inspire ID: 2802565

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 110 (2024) 5, 052012

Beams: * *

Beam energies: ANY

Run details: - Any process producing D_s+

Measurement of the q2 spectrum in the decay Ds+ → K0e+νe by BES-III. The data are from Table 5 in the paper.

Source code:BESIII_2024_I2802565.cc

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

namespace Rivet {


  /// @brief  q^2 in D_s+ -> K0 e+ nu_e
  class BESIII_2024_I2802565 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2024_I2802565);


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

    /// Book histograms and initialise projections before the run
    void init() {

      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::pid == 431);
      declare(ufs, "UFS");
      DecayedParticles DS(ufs);
      DS.addStable(PID::PI0);
      DS.addStable(PID::K0S);
      DS.addStable(PID::ETA);
      DS.addStable(PID::ETAPRIME);
      declare(DS, "DS");

      // Book histograms
      book(_h_q2, 1, 1, 1);
      book(_nD, "/TMP/nD");
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode1 = {{310, 1}, {-11, 1}, {12, 1}};
      static const map<PdgId, unsigned int>& mode2 = {{130, 1}, {-11, 1}, {12, 1}};
      static const map<PdgId, unsigned int>& mode3 = {{311, 1}, {-11, 1}, {12, 1}};
      DecayedParticles DS = apply<DecayedParticles>(event, "DS");
      // loop over particles
      for (unsigned int ix = 0; ix < DS.decaying().size(); ++ix) {
        _nD->fill();
        if (DS.modeMatches(ix, 3, mode1)) {
          _h_q2->fill((DS.decaying()[ix].momentum() - DS.decayProducts()[ix].at(310)[0].momentum()).mass2());
        }
        else if (DS.modeMatches(ix, 3, mode2)) {
          _h_q2->fill((DS.decaying()[ix].momentum() - DS.decayProducts()[ix].at(130)[0].momentum()).mass2());
        }
        else if (DS.modeMatches(ix, 3, mode3)) {
          _h_q2->fill((DS.decaying()[ix].momentum() - DS.decayProducts()[ix].at(311)[0].momentum()).mass2());
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // normalise to width in inverse ns
      scale(_h_q2, 1. / 0.504e-3 / *_nD);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_q2;
    CounterPtr _nD;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BESIII_2024_I2802565);

}