Rivet analyses

A Measurement of K*± (892) production in hadronic Z0 decays

Experiment: OPAL (LEP)

Inspire ID: 342766

Status: VALIDATED

Authors: - Simone Amoroso

References: - Phys.Lett. B305 (1993) 407-414 - DOI: 10.1016/0370-2693(93)91075-X

Beams: e+ e-

Beam energies: (45.6, 45.6)GeV

Run details: - electron positron collisions at the Z0 resonance with hadronic decays

OPAL measurement of the inclusive cross section for $K^{*} (892) $production in hadronic decays of the Z0

Source code:OPAL_1993_I342766.cc

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

namespace Rivet {


  /// @brief A Measurement of K*+- (892) production in hadronic Z0 decays
  /// @author Simone Amoroso
  class OPAL_1993_I342766 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(OPAL_1993_I342766);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(Beam(), "Beams");
      declare(ChargedFinalState(), "FS");
      declare(UnstableParticles(), "UFS");
      // Book histograms
      book(_histXeKStar892, 1, 1, 1);
      book(_histMeanKStar892, 2, 1, 1);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {

      const FinalState& fs = apply<FinalState>(event, "FS");
      const size_t numParticles = fs.particles().size();

      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
      if (numParticles < 2) {
        MSG_DEBUG("Failed leptonic event cut");
        vetoEvent;
      }
      MSG_DEBUG("Passed leptonic event cut");

      // Get beams and average beam momentum
      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
      const double meanBeamMom = 0.5*(beams.first.p3().mod() + beams.second.p3().mod());
      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);

      // Final state of unstable particles to get particle spectra
      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");

      for (const Particle& p : ufs.particles(Cuts::abspid==323)) {
        const double xp = p.p3().mod()/meanBeamMom;
        _histXeKStar892->fill(xp);
        _histMeanKStar892->fill(Ecm);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_histXeKStar892, 1./sumOfWeights());
      scale(_histMeanKStar892, 1./sumOfWeights());
    }

    /// @}


  private:

    /// @name Histograms
    Histo1DPtr _histXeKStar892;
    BinnedHistoPtr<string> _histMeanKStar892;
    const string Ecm = "91.2";

  };



  RIVET_DECLARE_PLUGIN(OPAL_1993_I342766);


}