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DELPHI_1999_S3960137

Measurement of inclusive $\rho^0$, $f_0(980)$, $f_2(1270)$, $K^{*0}_2(1430)$ and $f'_2(1525)$ production in $Z^0$ decays
Experiment: DELPHI (LEP 1)
Inspire ID: 482816
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett.B449:364-382,1999
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)

DELPHI results for the production of $\rho^0$, $f_0(980)$, $f_2(1270)$, $K^{*0}_2(1430)$ and $f'_2(1525)$ in $Z^0$ decays. Only the identified particle spectra for $\rho^0$, $f_0(980)$ and $f_2(1270)$ are implemented.

Source code: DELPHI_1999_S3960137.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/Beam.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/UnstableFinalState.hh"

namespace Rivet {


  /// @brief DELPHI rho,f_0 and f_2 fragmentation function paper
  /// @author Peter Richardson
  class DELPHI_1999_S3960137 : public Analysis {
  public:

    /// Constructor
    DELPHI_1999_S3960137()
      : Analysis("DELPHI_1999_S3960137")
    {}


    /// @name Analysis methods
    //@{

    void init() {
      declare(Beam(), "Beams");
      declare(ChargedFinalState(), "FS");
      declare(UnstableFinalState(), "UFS");
      _histXpRho = bookHisto1D( 1, 1, 1);
      _histXpf0  = bookHisto1D( 1, 1, 2);
      _histXpf2  = bookHisto1D( 1, 1, 3);
    }


    void analyze(const Event& e) {
      // First, veto on leptonic events by requiring at least 4 charged FS particles
      const FinalState& fs = apply<FinalState>(e, "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 event weight for histo filling
      const double weight = e.weight();

      // Get beams and average beam momentum
      const ParticlePair& beams = apply<Beam>(e, "Beams").beams();
      const double meanBeamMom = ( beams.first.p3().mod() +
                                   beams.second.p3().mod() ) / 2.0;
      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);

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

      foreach (const Particle& p, ufs.particles()) {
        const int id = p.abspid();
        double xp = p.p3().mod()/meanBeamMom;
        switch (id) {
        case 9010221:
          _histXpf0->fill(xp, weight);
          break;
        case 225:
          _histXpf2->fill(xp, weight);
          break;
        case 113:
          _histXpRho->fill(xp, weight);
          break;
        }
      }
    }


    /// Finalize
    void finalize() {
      scale(_histXpf0 , 1./sumOfWeights());
      scale(_histXpf2 , 1./sumOfWeights());
      scale(_histXpRho, 1./sumOfWeights());
    }

    //@}


  private:

      Histo1DPtr _histXpf0;
      Histo1DPtr _histXpf2;
      Histo1DPtr _histXpRho;
    //@}

  };

  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(DELPHI_1999_S3960137);

}