Rivet analyses

Charm meson spectra in e+e− collisions at 29 GeV

Experiment: HRS (PEP)

Inspire ID: 23360

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B206 (1988) 551-556, 1988

Beams: e+ e-

Beam energies: (14.5, 14.5)GeV

Run details: - Hadronic e+e- events at $\sqrt{s} = 29.$ GeV

D*±, D0, D̄0 and D± meson momentum spectrum measured at $\sqrt{s} = 29.$ GeV using the HRS detector at PEP. Only the spectra are implemented, not the electroweak asymmetries.

Source code:HRS_1988_I23360.cc

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

namespace Rivet {


  /// @brief Charm meson spectra at 29 GeV
  class HRS_1988_I23360 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(HRS_1988_I23360);


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

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

      // Initialise and register projections
      declare(Beam(), "Beams");
      declare(UnstableParticles(), "UFS");
      const ChargedFinalState cfs;
      declare(cfs, "CFS");

      // Book histograms
      book(_h_Dstar1, 1, 1, 1);
      book(_h_Dstar2, 1, 1, 2);
      book(_h_D0, 2, 1, 1);
      book(_h_Dp, 2, 1, 2);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const ChargedFinalState& cfs = apply<ChargedFinalState>(event, "CFS");
      int nch = cfs.particles().size();
      if (nch < 5) vetoEvent;
      // Get beams and average beam momentum
      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
      const double meanBeamMom = (beams.first.p3().mod() + beams.second.p3().mod()) / 2.0;
      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);

      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
      for (const Particle& p :
           ufs.particles(Cuts::abspid == 413 || Cuts::abspid == 421 || Cuts::abspid == 411)) {
        double xE = p.E() / meanBeamMom;
        int id = abs(p.pid());
        if (id == 413) {
          _h_Dstar1->fill(xE);
          _h_Dstar2->fill(xE);
        }
        else if (id == 421) {
          _h_D0->fill(xE);
        }
        else if (id == 411) {
          _h_Dp->fill(xE);
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      double fact = sqr(sqrtS()) * crossSection() / sumOfWeights() / microbarn;
      scale(_h_Dstar1, fact);
      normalize(_h_Dstar2);
      scale(_h_D0, fact);
      scale(_h_Dp, fact);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_Dstar1, _h_Dstar2, _h_D0, _h_Dp;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(HRS_1988_I23360);


}