Rivet analyses

Mass distributions in the decays D⁰ → K⁺K⁻π⁺π⁻

Experiment: LHCB (LHC)

Inspire ID: 1704426

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - JHEP 02 (2019) 126

Beams: * *

Beam energies: ANY

Run details: - Any process producing D0 mesons

Measurement of the mass distributions in the decay D⁰ → K⁺K⁻π⁺π⁻ by LHCb. The data were extracted from the plots in the paper. It is also not clear that any resolution effects have been unfolded.

Source code:`LHCB_2018_I1704426.cc`

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

namespace Rivet {


  /// @brief
  class LHCB_2018_I1704426 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2018_I1704426);


    /// @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) book(_h[ix], 1, 1, 1 + ix);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // define the decay mode
      static const map<PdgId, unsigned int>& mode = {{321, 1}, {-321, 1}, {211, 1}, {-211, 1}};
      DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
      // loop over particles
      for (unsigned int ix = 0; ix < D0.decaying().size(); ++ix) {
        int sign = D0.decaying()[ix].pid() / 421;
        if (D0.modeMatches(ix, 4, mode)) {
          const Particles& Kp = D0.decayProducts()[ix].at(sign * 321);
          const Particles& Km = D0.decayProducts()[ix].at(-sign * 321);
          const Particles& pip = D0.decayProducts()[ix].at(sign * 211);
          const Particles& pim = D0.decayProducts()[ix].at(-sign * 211);
          double mpipi = (pip[0].momentum() + pim[0].momentum()).mass();
          if (mpipi > 0.4802 && mpipi < 0.5072) continue;
          _h[0]->fill((Kp[0].momentum() + Km[0].momentum()).mass() / MeV);
          _h[1]->fill(mpipi / MeV);
        }
      }
    }


    /// 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(LHCB_2018_I1704426);

}

Rivet analyses

Mass distributions in the decays D0 → K+K−π+π−

Source code:LHCB_2018_I1704426.cc

Mass distributions in the decays D⁰ → K⁺K⁻π⁺π⁻

Source code:`LHCB_2018_I1704426.cc`