Rivet analyses

Dalitz decays D⁰ → π⁺π⁻η and D⁺ → π⁺π⁰η

Experiment: BESIII (BEPC)

Inspire ID: 2777242

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 110 (2024) 11, L111102 - arXiv: 2404.09219

Beams: * *

Beam energies: ANY

Run details: - Any process producing D+/D0 mesons

Measurement of the mass distributions in the decays D⁰ → π⁺π⁻η and D⁺ → π⁺π⁰η by the BESIII collaboration. The data were read from the plots in the paper and resolution/efficiency effects have not been unfolded.

Source code:`BESIII_2024_I2777242.cc`

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

namespace Rivet {


  /// @brief D0 -> pi+pi0eta and D+ -> pi+pi-eta
  class BESIII_2024_I2777242 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2024_I2777242);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 411 || Cuts::abspid == 421);
      declare(ufs, "UFS");
      DecayedParticles DD(ufs);
      DD.addStable(PID::PI0);
      DD.addStable(PID::K0S);
      DD.addStable(PID::ETA);
      declare(DD, "DD");
      // // histograms
      for (unsigned int ix = 0; ix < 2; ++ix) {
        for (unsigned int iy = 0; iy < 2; ++iy) book(_h_etapi[ix][iy], 1, 1 + ix, 1 + iy);
        book(_h_pipi[ix], 1, 1 + ix, 3);
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int> mode[2] = {{{211, 1}, {-211, 1}, {221, 1}},
                                                       {{211, 1}, {111, 1}, {221, 1}}};
      static const map<PdgId, unsigned int> modeCC[2] = {{{211, 1}, {-211, 1}, {221, 1}},
                                                         {{-211, 1}, {111, 1}, {221, 1}}};
      DecayedParticles DD = apply<DecayedParticles>(event, "DD");
      // loop over particles
      for (unsigned int ix = 0; ix < DD.decaying().size(); ++ix) {
        unsigned int ip = DD.decaying()[ix].abspid() == 411 ? 1 : 0;
        int sign = 1;
        if (DD.decaying()[ix].pid() > 0 && DD.modeMatches(ix, 3, mode[ip])) {
          sign = 1;
        }
        else if (DD.decaying()[ix].pid() < 0 && DD.modeMatches(ix, 3, modeCC[ip])) {
          sign = -1;
        }
        else
          continue;
        const Particle& eta = DD.decayProducts()[ix].at(221)[0];
        const Particle& pim = ip == 0 ? DD.decayProducts()[ix].at(-sign * 211)[0]
                                      : DD.decayProducts()[ix].at(111)[0];
        const Particle& pip = DD.decayProducts()[ix].at(sign * 211)[0];
        double mpipi = (pim.momentum() + pip.momentum()).mass();
        // apply KS0 cut
        if (ip == 0 && abs(mpipi - .497611) < 0.03) continue;
        // mass dists
        _h_pipi[ip]->fill(mpipi);
        _h_etapi[ip][0]->fill((eta.momentum() + pip.momentum()).mass());
        _h_etapi[ip][1]->fill((eta.momentum() + pim.momentum()).mass());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_pipi);
      normalize(_h_etapi);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_pipi[2], _h_etapi[2][2];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BESIII_2024_I2777242);

}

Rivet analyses

Dalitz decays D0 → π+π−η and D+ → π+π0η

Source code:BESIII_2024_I2777242.cc

Dalitz decays D⁰ → π⁺π⁻η and D⁺ → π⁺π⁰η

Source code:`BESIII_2024_I2777242.cc`