Rivet analyses

Σ− and Λ(1520) production at the Z0 pole from DELPHI

Experiment: DELPHI (LEP)

Inspire ID: 524694

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B475 (2000) 429-447, 2000

Beams: e+ e-

Beam energies: (45.6, 45.6)GeV

Run details: - Hadronic Z decay events generated on the Z pole ($\sqrt{s} = 91.2$ GeV)

Measurement of the Σ− and Λ0(1520) scaled momentum distributions by DELPHI at LEP 1

Source code:DELPHI_2000_I524694.cc

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

namespace Rivet {


  /// @brief Sigma- and Lambda(1520) ar Z pole
  class DELPHI_2000_I524694 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(DELPHI_2000_I524694);


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

    /// Book histograms and initialise projections before the run
    void init() {
      declare(Beam(), "Beams");
      declare(UnstableParticles(), "UFS");
      book(_histXpSigma,  1, 1, 1);
      book(_histXpLambda,  3, 1, 1);
    }


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


      // Get event weight for histo filling

      // 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;

      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
      for (const Particle& p : ufs.particles()) {
        const int id = p.abspid();
        double xp = p.p3().mod()/meanBeamMom;
        switch (id) {
        case 3112:
          _histXpSigma->fill(xp);
      break;
        case 102134:
          _histXpLambda->fill(xp);
      break;
    }
      }

    }


    /// Normalise histograms etc., after the run
    void finalize() {
      double fact = 1./sumOfWeights();
      scale(_histXpSigma , fact);
      scale(_histXpLambda, fact);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _histXpSigma;
    Histo1DPtr _histXpLambda;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(DELPHI_2000_I524694);


}