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CMD2_1995_I406880

Cross section for $e^+e^-\to$ $K^+K^-$, $K_S^0K_L^0$, $\pi^+\pi^-\pi^0$ and $\eta\gamma$ near the $\phi$ resonance
Experiment: CMD2 (VEPP-2M)
Inspire ID: 406880
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. B364 (1995) 199-206, 1995
Beams: e+ e-
Beam energies: ANY
Run details:
  • e+e- to hadrons

Source code: CMD2_1995_I406880.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 Add a short analysis description here
 10  class CMD2_1995_I406880 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(CMD2_1995_I406880);
 15
 16
 17    /// @name Analysis methods
 18    /// @{
 19
 20    /// Book histograms and initialise projections before the run
 21    void init() {
 22
 23      // Initialise and register projections
 24      declare(FinalState(), "FS");
 25      declare(UnstableParticles(), "UFS");
 26      book(_nKpKm, "TMP/KpKm");
 27      book(_nK0K0, "TMP/K0K0");
 28      book(_n3pi, "TMP/3pi");
 29      book(_numEtaGamma, "TMP/EtaGamma");
 30    }
 31
 32    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
 33      for (const Particle &child : p.children()) {
 34	if(child.children().empty()) {
 35	  --nRes[child.pid()];
 36	  --ncount;
 37	}
 38	else
 39	  findChildren(child,nRes,ncount);
 40      }
 41    }
 42
 43    /// Perform the per-event analysis
 44    void analyze(const Event& event) {
 45      const FinalState& fs = apply<FinalState>(event, "FS");
 46
 47      map<long,int> nCount;
 48      int ntotal(0);
 49      for (const Particle& p : fs.particles()) {
 50	nCount[p.pid()] += 1;
 51	++ntotal;
 52      }
 53      if(ntotal==2) {
 54	if(nCount[321]==1 && nCount[-321]==1)
 55	  _nKpKm->fill();
 56	else if(nCount[130]==1 && nCount[310]==1)
 57	  _nK0K0->fill();
 58      }
 59      else if(ntotal==3 && nCount[211] == 1 && nCount[-211] == 1 && nCount[111] == 1)
 60	_n3pi->fill();
 61
 62      const FinalState& ufs = apply<FinalState>(event, "UFS");
 63      for (const Particle& p : ufs.particles()) {
 64	if(p.children().empty()) continue;
 65	// find the omega
 66	if(p.pid()==221) {
 67	  map<long,int> nRes = nCount;
 68	  int ncount = ntotal;
 69	  findChildren(p,nRes,ncount);
 70	  // eta pi+pi-
 71	  if(ncount!=1) continue;
 72	  bool matched = true;
 73          for(auto const & val : nRes) {
 74	    if(val.first==22) {
 75	      if(val.second !=1) {
 76		matched = false;
 77		break;
 78	      }
 79	    }
 80	    else if(val.second!=0) {
 81	      matched = false;
 82	      break;
 83	    }
 84	  }
 85	  if(matched)
 86	    _numEtaGamma->fill();
 87	}
 88      }
 89    }
 90
 91
 92    /// Normalise histograms etc., after the run
 93    void finalize() {
 94      for (unsigned int ix=1;ix<5;++ix) {
 95        double sigma = 0., error = 0.;
 96        if(ix==1) {
 97          sigma = _nKpKm->val();
 98          error = _nKpKm->err();
 99        }
100        else if(ix==2) {
101          sigma = _nK0K0->val();
102          error = _nK0K0->err();
103        }
104        else if(ix==3) {
105          sigma = _n3pi->val();
106          error = _n3pi->err();
107        }
108        else if(ix==4) {
109          sigma = _numEtaGamma->val();
110          error = _numEtaGamma->err();
111        }
112        sigma *= crossSection()/ sumOfWeights() /nanobarn;
113        error *= crossSection()/ sumOfWeights() /nanobarn;
114        Estimate1DPtr mult;
115        book(mult, 1, 1, ix);
116        for (auto& b : mult->bins()) {
117          if (inRange(sqrtS()/MeV, b.xMin(), b.xMax())) {
118            b.set(sigma, error);
119          }
120        }
121      }
122    }
123    /// @}
124
125
126    /// @name Histograms
127    /// @{
128    CounterPtr _nKpKm,_nK0K0,_n3pi,_numEtaGamma;
129    /// @}
130
131
132  };
133
134
135  RIVET_DECLARE_PLUGIN(CMD2_1995_I406880);
136
137
138}