Rivet analyses

π0 spectrum in e+e− at 34.4 GeV

Experiment: TASSO (Petra)

Inspire ID: 230950

Status: VALIDATED

Authors: - Peter Richardson

References: - Z.Phys. C33 (1986) 13, 1986

Beams: e+ e-

Beam energies: (17.2, 17.2)GeV

Run details: - e+ e- to hadrons

Measurement of the π0 spectrum in e+e− collisions for a centre-of-mass energy of 34.4 GeV by the TASSO experiment at Petra.

Source code:TASSO_1986_I230950.cc

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

namespace Rivet {


  /// @brief Add a short analysis description here
  class TASSO_1986_I230950 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(TASSO_1986_I230950);


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

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

      // Initialise and register projections
      declare(Beam(), "Beams");
      declare(UnstableParticles(), "UFS");

      // Book histograms
      book(_h_p, 1, 1, 1);
      book(_h_x, 2, 1, 1);

    }


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

      for (const Particle& p : apply<UnstableParticles>(event, "UFS").
         particles(Cuts::pid==PID::PI0)) {
      double modp = p.p3().mod();
      double xE = p.E()/meanBeamMom;
      double beta = modp/p.E();
      _h_p->fill(modp);
      _h_x->fill(xE, 1./beta);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_h_p, crossSection()/nanobarn/sumOfWeights());
      scale(_h_x, sqr(sqrtS())*crossSection()/microbarn/sumOfWeights());
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_p, _h_x;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(TASSO_1986_I230950);


}