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TASSO_1982_I177174

Charged Particle spectra in $e^+e^-$ collisions in $e^+e^-$ at 12, 14, 22, 25, 30, 34 and 35 GeV
Experiment: TASSO (Petra)
Inspire ID: 177174
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. 114B (1982) 65
Beams: e+ e-
Beam energies: (6.0, 6.0); (7.0, 7.0); (11.0, 11.0); (12.5, 12.5); (15.0, 15.0); (17.0, 17.0); (17.5, 17.5) GeV
Run details:
  • e+ e- to hadrons

Measurement of the charged particle spectra in $e^+e^-$ collisions in $e^+e^-$ at 12, 14, 22, 25, 30, 34 and 35 GeV by the TASSO experiment at Petra.

Source code: TASSO_1982_I177174.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/Beam.hh"

namespace Rivet {


  /// @brief Charged particle spectra for a range of energies
  class TASSO_1982_I177174 : public Analysis {
  public:

    /// Constructor
    DEFAULT_RIVET_ANALYSIS_CTOR(TASSO_1982_I177174);


    /// @name Analysis methods
    //@{

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(Beam(), "Beams");
      declare(ChargedFinalState(), "FS");
      if(fuzzyEquals(sqrtS()/GeV, 12., 1e-3)) {
	book(_h_x2,2,1,1);
	book(_h_x3,3,1,1);
      }
      else if (fuzzyEquals(sqrtS()/GeV, 14., 1e-3)) {
	book(_h_x1,1,1,1);
	book(_h_x2,2,1,2);
	book(_h_x3,3,1,2);
      }
      else if (fuzzyEquals(sqrtS()/GeV, 22., 1e-3)) {
	book(_h_x1,1,1,2);
	book(_h_x2,2,1,3);
	book(_h_x3,3,1,3);
      }
      else if (fuzzyEquals(sqrtS()/GeV, 25., 1e-3)) {
	book(_h_x2,2,1,4);
	book(_h_x3,3,1,4);
      }
      else if (fuzzyEquals(sqrtS()/GeV, 30., 1e-3)) {
	book(_h_x2,2,1,5);
	book(_h_x3,3,1,5);
      }
      else if (fuzzyEquals(sqrtS()/GeV, 34., 1e-3)) {
	book(_h_x2,2,1,6);
	book(_h_x3,3,1,6);
      }
      else if (fuzzyEquals(sqrtS()/GeV, 35., 1e-3)) {
        book(_h_x2, 2,1,7);
        book(_h_x3, 3,1,7);
      }

      if(inRange(sqrtS()/GeV, 29.9,36.7))
        book(_h_x1, 1,1,3);

      if(_h_x1==Histo1DPtr() && _h_x2==Histo1DPtr() && _h_x3==Histo1DPtr())
      	MSG_ERROR("Beam energy not supported!");

    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // First, veto on leptonic events by requiring at least 4 charged FS particles
      const ChargedFinalState& fs = apply<ChargedFinalState>(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 = ( beams.first.p3().mod() +
                                   beams.second.p3().mod() ) / 2.0;
      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
      
      for (const Particle& p : fs.particles()) {
	double xp = p.p3().mod()/meanBeamMom;
	if(_h_x1!=Histo1DPtr()) _h_x1->fill(xp);
	if(_h_x2!=Histo1DPtr()) _h_x2->fill(xp);
	if(_h_x3!=Histo1DPtr()) _h_x3->fill(xp);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {

      scale(_h_x1, crossSection()/microbarn/sumOfWeights()*sqr(sqrtS()));
      scale(_h_x2, crossSection()/microbarn/sumOfWeights()*sqr(sqrtS()));
      scale(_h_x3, 1./sumOfWeights());

    }

    //@}


    /// @name Histograms
    //@{
    Histo1DPtr _h_x1,_h_x2,_h_x3;
    //@}


  };


  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(TASSO_1982_I177174);


}