rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

HRS_1985_I201482

Event shapes in $e^+e^-$ collisions at 29 GeV
Experiment: HRS (PEP)
Inspire ID: 201482
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev. D31 (1985) 1, 1985
Beams: e+ e-
Beam energies: (14.5, 14.5) GeV
Run details:
  • Hadronic e+e- events at $\sqrt{s} = 29.$ GeV

Measurement of a range of event shapes at 29 GeV by the HRS experiment. The event are seperate into two ($S\leq0.25$, $A\leq0.1$) and jet three($S>0.25$, $A\leq0.1$) jet regions. The mean values of event shapes are not implemented.

Source code: HRS_1985_I201482.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/Beam.hh"
  4#include "Rivet/Projections/ChargedFinalState.hh"
  5#include "Rivet/Projections/Sphericity.hh"
  6#include "Rivet/Projections/Thrust.hh"
  7
  8namespace Rivet {
  9
 10
 11  /// @brief event shapes at 29 GeV
 12  class HRS_1985_I201482 : public Analysis {
 13  public:
 14
 15    /// Constructor
 16    RIVET_DEFAULT_ANALYSIS_CTOR(HRS_1985_I201482);
 17
 18
 19    /// @name Analysis methods
 20    /// @{
 21
 22    /// Book histograms and initialise projections before the run
 23    void init() {
 24
 25      // Initialise and register projections
 26      declare(Beam(), "Beams");
 27      const ChargedFinalState cfs;
 28      declare(cfs, "FS");
 29      declare(Sphericity(cfs), "Sphericity");
 30      const Thrust thrust(cfs);
 31      declare(thrust, "Thrust");
 32
 33      // Book histograms
 34      book(_histSphericity,  1, 1, 1);
 35      book(_histThrust    ,  3, 1, 1);
 36      book(_histThrust2Jet,  4, 1, 1);
 37      book(_histAplanarity,  6, 1, 1);
 38      book(_histZ         , 10, 1, 1);
 39      book(_histZ2Jet     , 11, 1, 1);
 40      book(_histZScale    , 12, 1, 1);
 41      book(_histZJet[0]   , 13, 1, 1);
 42      book(_histZJet[1]   , 14, 1, 1);
 43      book(_histZJet[2]   , 15, 1, 1);
 44      book(_histXFeyn     , 16, 1, 1);
 45      book(_histXFeyn2Jet , 17, 1, 1);
 46      book(_histRap[0]    , 19, 1, 1);
 47      book(_histRap[1]    , 20, 1, 1);
 48      book(_histPtT       , 22, 1, 1);
 49      book(_histPtT2Jet   , 23, 1, 1);
 50      book(_histPtTIn     , 24, 1, 1);
 51      book(_histPtTOut    , 25, 1, 1);
 52      book(_wSum ,"TMP/wSum");
 53      book(_wSum2,"TMP/wSum2");
 54
 55      _axes[0] = YODA::Axis<double>({-5.0, -4.0, -3.5, -3.0, -2.75, -2.5, -2.3, -2.0, -1.75, -1.5,
 56                                      -1.25, -1.0, -0.75, -0.5, -0.25, 0.0, 0.25, 0.5, 0.75, 1.0,
 57                                      1.25, 1.5, 1.75, 2.0, 2.3, 2.5, 2.75, 3.0, 3.5, 4.0, 5.0});
 58      _axes[1] = YODA::Axis<double>({-4.0, -3.5, -3.0, -2.75, -2.5, -2.25, -2.0, -1.75, -1.5,
 59                                     -1.25, -1.0, -0.75, -0.5, -0.25, 0.0, 0.25, 0.5, 0.75,
 60                                      1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0, 3.5, 4.0});
 61    }
 62
 63
 64    /// Perform the per-event analysis
 65    void analyze(const Event& event) {
 66      if (_edges[0].empty()) {
 67        _edges[0] = _histRap[0]->xEdges();
 68        _edges[1] = _histRap[1]->xEdges();
 69      }
 70      // require 5 charged particles
 71      const FinalState& fs = apply<FinalState>(event, "FS");
 72      const size_t numParticles = fs.particles().size();
 73      if(numParticles<5) vetoEvent;
 74      // Get beams and average beam momentum
 75      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
 76      const double meanBeamMom = ( beams.first.p3().mod() +
 77                                   beams.second.p3().mod() ) / 2.0;
 78      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
 79      // calc thrust and sphericity
 80      const Thrust& thrust = apply<Thrust>(event, "Thrust");
 81      Vector3 axis = thrust.thrustAxis();
 82      const Sphericity& sphericity = apply<Sphericity>(event, "Sphericity");
 83      // identify two and three jet regions
 84      bool twoJet   = sphericity.sphericity()<=0.25 && sphericity.aplanarity()<=0.1;
 85      //bool threeJet = sphericity.sphericity() >0.25 && sphericity.aplanarity()<=0.1;
 86      _wSum->fill();
 87      if (twoJet) _wSum2->fill();
 88      // basic event shapes
 89      _histSphericity->fill(sphericity.sphericity());
 90      _histThrust    ->fill(thrust.thrust());
 91      _histAplanarity->fill(sphericity.aplanarity());
 92      if(twoJet)  _histThrust2Jet->fill(thrust.thrust());
 93      double pTSqIn  = 0.;
 94      double pTSqOut = 0.;
 95      unsigned int iPlus(0),iMinus(0);
 96      // single particle  dists
 97      for(const Particle & p : sortBy(fs.particles(),cmpMomByP)) {
 98        const double z  = p.p3().mod()/meanBeamMom;
 99        const double momT = axis.dot(p.p3());
100        const double xF = fabs(momT)/meanBeamMom;
101        const double energy = p.E();
102        const double rap = 0.5 * std::log((energy + momT) / (energy - momT));
103        const double pTin  = dot(p.p3(), thrust.thrustMajorAxis());
104        const double pTout = dot(p.p3(), thrust.thrustMinorAxis());
105        const double pT2 = sqr(pTin)+sqr(pTout);
106        pTSqIn  += sqr(dot(p.p3(), sphericity.sphericityMajorAxis()));
107        pTSqOut += sqr(dot(p.p3(), sphericity.sphericityMinorAxis()));
108        _histZ->fill(z);
109        _histZScale->fill(z);
110        _histXFeyn ->fill(xF, z);
111        _histRap[0]->fill(map2string(rap, 0));
112        _histPtT->fill(pT2);
113        if(twoJet) {
114          _histZ2Jet->fill(z);
115          _histXFeyn2Jet->fill(xF, z);
116          _histRap[1]->fill(map2string(rap, 1));
117          _histPtT2Jet->fill(pT2);
118          if(momT>0.&&iPlus<3) {
119            _histZJet[iPlus]->fill(z);
120            iPlus+=1;
121          }
122          else if(momT<0.&&iMinus<3) {
123            _histZJet[iMinus]->fill(z);
124            iMinus+=1;
125          }
126        }
127      }
128      _histPtTIn ->fill(pTSqIn /numParticles);
129      _histPtTOut->fill(pTSqOut/numParticles);
130    }
131
132
133    /// Normalise histograms etc., after the run
134    void finalize() {
135
136      normalize(_histSphericity);
137      normalize(_histThrust);
138      normalize(_histThrust2Jet);
139      normalize(_histAplanarity);
140      scale(_histZ, 1./ *_wSum);
141      scale(_histZScale,    sqr(sqrtS())*crossSection()/microbarn/sumOfWeights());
142      scale(_histXFeyn,     1./M_PI/ *_wSum);
143      scale(_histRap[0],    1./ *_wSum);
144      scale(_histZ2Jet,     1./ *_wSum2);
145      scale(_histXFeyn2Jet, 1./M_PI/ *_wSum2);
146      scale(_histRap[1],    1./ *_wSum2);
147      scale(_histPtT,       1./ *_wSum);
148      scale(_histPtT2Jet,   1./ *_wSum2);
149      scale(_histPtTIn,     1./ *_wSum);
150      scale(_histPtTOut,    1./ *_wSum);
151      for (size_t i=0; i<3; ++i) {
152        scale(_histZJet[i], 0.5/ *_wSum2);
153      }
154    }
155
156    /// @}
157
158    string map2string(const double value, const size_t k) const {
159      const size_t idx = _axes[k].index(value);
160      if (idx && idx <= _edges[k].size())  return _edges[k][idx-1];
161      return "OTHER";
162    }
163
164
165    /// @name Histograms
166    /// @{
167    Histo1DPtr _histSphericity, _histThrust, _histThrust2Jet, _histAplanarity,
168      _histZ, _histZ2Jet, _histZScale, _histXFeyn, _histXFeyn2Jet,
169      _histPtT, _histPtT2Jet, _histPtTIn, _histPtTOut, _histZJet[3];
170    BinnedHistoPtr<string> _histRap[2];
171    CounterPtr _wSum,_wSum2;
172
173    YODA::Axis<double> _axes[2];
174    vector<string> _edges[2];
175
176    /// @}
177
178
179  };
180
181
182  RIVET_DECLARE_PLUGIN(HRS_1985_I201482);
183
184
185}