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SND_2016_I1473343

Cross section for $e^+e^-\to\eta\omega$ for energies below 2 GeV
Experiment: SND (VEPP-2M)
Inspire ID: 1473343
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev. D94 (2016) no.9, 092002
Beams: e+ e-
Beam energies: ANY
Run details:
  • e+ e- to hadrons

Cross section for $e^+e^-\to\eta\omega$ for energies below 2 GeV

Source code: SND_2016_I1473343.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/FinalState.hh"
  4#include "Rivet/Projections/UnstableParticles.hh"
  5
  6namespace Rivet {
  7
  8
  9  /// @brief e+e- -> omega eta
 10  class SND_2016_I1473343 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(SND_2016_I1473343);
 15
 16
 17    /// @name Analysis methods
 18    //@{
 19
 20    /// Book histograms and initialise projections before the run
 21    void init() {
 22      // Initialise and register projections
 23      declare(FinalState(), "FS");
 24      declare(UnstableParticles(), "UFS");
 25      book(_nOmegaEta, "/TMP/nOmegaEta");
 26    }
 27
 28    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
 29      for (const Particle &child : p.children()) {
 30	if(child.children().empty()) {
 31	  nRes[child.pid()]-=1;
 32	  --ncount;
 33	}
 34	else
 35	  findChildren(child,nRes,ncount);
 36      }
 37    }
 38
 39    /// Perform the per-event analysis
 40    void analyze(const Event& event) {
 41      const FinalState& fs = apply<FinalState>(event, "FS");
 42      map<long,int> nCount;
 43      int ntotal(0);
 44      for (const Particle& p : fs.particles()) {
 45	nCount[p.pid()] += 1;
 46	++ntotal;
 47      }
 48      const FinalState& ufs = apply<FinalState>(event, "UFS");
 49      for (const Particle& p : ufs.particles()) {
 50	if(p.children().empty()) continue;
 51	if(p.pid()!=223) continue;
 52	map<long,int> nRes = nCount;
 53	int ncount = ntotal;
 54	findChildren(p,nRes,ncount);
 55	for (const Particle& p2 : ufs.particles()) {
 56	  if(p2.pid()!=221) continue;
 57	  map<long,int> nResB = nRes;
 58	  int ncountB = ncount;
 59	  findChildren(p2,nResB,ncountB);
 60	  if(ncountB!=0) continue;
 61	  bool matched2 = true;
 62	  for(auto const & val : nResB) {
 63	    if(val.second!=0) {
 64	      matched2 = false;
 65	      break;
 66	    }
 67	  }
 68	  if(matched2) {
 69	    _nOmegaEta->fill();
 70	    break;
 71	  }
 72	}
 73      }
 74    }
 75
 76
 77    /// Normalise histograms etc., after the run
 78    void finalize() {
 79      double sigma = _nOmegaEta->val();
 80      double error = _nOmegaEta->err();
 81      sigma *= crossSection()/ sumOfWeights() /nanobarn;
 82      error *= crossSection()/ sumOfWeights() /nanobarn; 
 83      Scatter2D temphisto(refData(1, 1, 1));
 84      Scatter2DPtr mult;
 85      book(mult, 1, 1, 1);
 86      for (size_t b = 0; b < temphisto.numPoints(); b++) {
 87	const double x  = temphisto.point(b).x();
 88	pair<double,double> ex = temphisto.point(b).xErrs();
 89	pair<double,double> ex2 = ex;
 90	if(ex2.first ==0.) ex2. first=0.0001;
 91	if(ex2.second==0.) ex2.second=0.0001;
 92	if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
 93	  mult->addPoint(x, sigma, ex, make_pair(error,error));
 94	}
 95	else {
 96	    mult->addPoint(x, 0., ex, make_pair(0.,.0));
 97	}
 98      }
 99    }
100    //@}
101
102
103    /// @name Histograms
104    //@{
105    CounterPtr _nOmegaEta;
106    //@}
107
108
109  };
110
111
112  // The hook for the plugin system
113  RIVET_DECLARE_PLUGIN(SND_2016_I1473343);
114
115
116}