Rivet Analyses Reference

TASSO_1987_I248660

Energy-Energy correlations between 12 and 46.8 GeV
Experiment: TASSO (Petra)
Inspire ID: 248660
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Z.Phys. C36 (1987) 349-361, 1987
Beams: e+ e-
Beam energies: (7.0, 7.0); (11.0, 11.0); (17.4, 17.4); (21.8, 21.8) GeV
Run details:
  • e+e- to hadrons at the relevant CMS energies. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples.

Measurement of the energy-energy correlation at centre-of-mass energies between 12 and 46.8 GeV. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples.

Source code: TASSO_1987_I248660.cc
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/Beam.hh"
#include "Rivet/Projections/FinalState.hh"

namespace Rivet {


  /// @brief for 14,22,34.8 and 43.5 GeV
  class TASSO_1987_I248660 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(TASSO_1987_I248660);


    /// @name Analysis methods
    //@{

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(FinalState(), "FS");

      // Book histograms
      unsigned int iloc(0);
      if(isCompatibleWithSqrtS(14.)) {
	iloc=1;
      }
      else if (isCompatibleWithSqrtS(22.)) {
	iloc=2;
      }
      else if (isCompatibleWithSqrtS(34.8)) {
	iloc=3;
      }
      else if (isCompatibleWithSqrtS(43.5)) {
	iloc=4;
      }
      else
	MSG_WARNING("CoM energy of events sqrt(s) = " << sqrtS()/GeV
                    << " doesn't match any available analysis energy .");
      assert(iloc!=0);
      book(_histEEC, iloc, 1, 1);
      book(_weightSum, "TMP/weightSum");
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // First, veto on leptonic events by requiring at least 4 charged FS particles
      const FinalState& fs = apply<FinalState>(event, "FS");
      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
      if ( fs.particles().size() < 2) {
        MSG_DEBUG("Failed leptonic event cut");
        vetoEvent;
      }
      MSG_DEBUG("Passed leptonic event cut");

      _weightSum->fill();
      double Evis = 0.0;
      for (const Particle& p : fs.particles()) {
        Evis += p.E();
      }
      double Evis2 = sqr(Evis);
      // (A)EEC
      // Need iterators since second loop starts at current outer loop iterator, i.e. no "foreach" here!
      for (Particles::const_iterator p_i = fs.particles().begin(); p_i != fs.particles().end(); ++p_i) {
        for (Particles::const_iterator p_j = p_i; p_j != fs.particles().end(); ++p_j) {
          const Vector3 mom3_i = p_i->momentum().p3();
          const Vector3 mom3_j = p_j->momentum().p3();
          const double energy_i = p_i->momentum().E();
          const double energy_j = p_j->momentum().E();
          const double cosij = dot(mom3_i.unit(), mom3_j.unit());
          double eec = (energy_i*energy_j) / Evis2;
	  if(p_i != p_j) eec *= 2.;
          _histEEC->fill(cosij, eec);
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_histEEC,  1.0/ *_weightSum);
    }

    //@}


    /// @name Histograms
    //@{
    Histo1DPtr _histEEC;
    CounterPtr _weightSum;
    //@}


  };


  // The hook for the plugin system
  RIVET_DECLARE_PLUGIN(TASSO_1987_I248660);


}