Rivet analyses

Mass distributions in J/ψ → ϕπ⁺π⁺ and ϕK⁺K⁻

Experiment: BESII (BEPC)

Inspire ID: 663288

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Lett.B 607 (2005) 243-253

Beams: * *

Beam energies: ANY

Run details: - Any process producing J/psi, originally e+e-

Mass distributions in J/ψ → ϕπ⁺π⁺ and ϕK⁺K⁻. The data were read from the figures in the paper and are not corrected for acceptance.

Source code:`BESII_2005_I663288.cc`

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

namespace Rivet {


  /// @brief J/psi -> phi pi+pi- K+K-
  class BESII_2005_I663288 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESII_2005_I663288);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 443);
      declare(ufs, "UFS");
      DecayedParticles PSI(ufs);
      PSI.addStable(333);
      declare(PSI, "PSI");
      // histograms
      for (unsigned int ix = 0; ix < 2; ++ix) {
        for (unsigned int iy = 0; iy < 2; ++iy) {
          book(_h_mass[ix][iy], 1 + ix, 1, 1 + iy);
        }
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // J/psi decay products
      DecayedParticles PSI = apply<DecayedParticles>(event, "PSI");
      if (PSI.decaying().size() != 1) vetoEvent;
      unsigned int imode = 0;
      if (PSI.modeMatches(0, 3, mode1))
        imode = 0;
      else if (PSI.modeMatches(0, 3, mode2))
        imode = 1;
      else
        vetoEvent;
      unsigned int iMeson = imode == 0 ? 211 : 321;
      const Particle& Mp = PSI.decayProducts()[0].at(iMeson)[0];
      const Particle& Mm = PSI.decayProducts()[0].at(-iMeson)[0];
      const Particle& phi = PSI.decayProducts()[0].at(333)[0];
      // mass histograms
      FourMomentum pX = Mp.momentum() + Mm.momentum();
      const double mX = pX.mass();
      _h_mass[imode][0]->fill(mX / GeV);
      _h_mass[imode][1]->fill((Mp.momentum() + phi.momentum()).mass() / GeV);
      _h_mass[imode][1]->fill((Mm.momentum() + phi.momentum()).mass() / GeV);
    }


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

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_mass[2][2];
    const map<PdgId, unsigned int> mode1 = {{333, 1}, {211, 1}, {-211, 1}};
    const map<PdgId, unsigned int> mode2 = {{333, 1}, {321, 1}, {-321, 1}};
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BESII_2005_I663288);

}

Rivet analyses

Mass distributions in J/ψ → ϕπ+π+ and ϕK+K−

Source code:BESII_2005_I663288.cc

Mass distributions in J/ψ → ϕπ⁺π⁺ and ϕK⁺K⁻

Source code:`BESII_2005_I663288.cc`