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DM2_1992_I339265

Cross section for $e^+e^-\to\pi^+\pi^-\pi^0$ and $\omega\pi^+\pi^-$ at energies between 1.35 and 2.4 GeV
Experiment: DM2 (DCI)
Inspire ID: 339265
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Z.Phys. C56 (1992) 15-20, 1992
Beams: e+ e-
Beam energies: ANY
Run details:
  • e+e- to hadrons

Measurement of the cross section for $e^+e^-\to\pi^+\pi^-\pi^0$ and $\omega\pi^+\pi^-$ at energies between 1.35 and 2.4 GeV.

Source code: DM2_1992_I339265.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 DM2_1992_I339265 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(DM2_1992_I339265);
 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(_n3pi, "TMP/3pi");
 27      book(_nomega, "TMP/omega");
 28    }
 29
 30
 31    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
 32      for (const Particle &child : p.children()) {
 33	if(child.children().empty()) {
 34	  --nRes[child.pid()];
 35	  --ncount;
 36	}
 37	else
 38	  findChildren(child,nRes,ncount);
 39      }
 40    }
 41
 42    /// Perform the per-event analysis
 43    void analyze(const Event& event) {
 44      const FinalState& fs = apply<FinalState>(event, "FS");
 45      
 46      map<long,int> nCount;
 47      int ntotal(0);
 48      for (const Particle& p : fs.particles()) {
 49	nCount[p.pid()] += 1;
 50	++ntotal;
 51      }
 52      if(ntotal==3 && nCount[211] == 1 && nCount[-211] == 1 && nCount[111] == 1)
 53	_n3pi->fill();
 54
 55      const FinalState& ufs = apply<FinalState>(event, "UFS");
 56      for (const Particle& p : ufs.particles()) {
 57	if(p.children().empty()) continue;
 58	// find the omega
 59	if(p.pid()==223) {
 60	  map<long,int> nRes = nCount;
 61	  int ncount = ntotal;
 62	  findChildren(p,nRes,ncount);
 63	  // omega pi+pi-
 64	  if(ncount!=2) continue;
 65	  bool matched = true;
 66	  for(auto const & val : nRes) {
 67	    if(abs(val.first)==211) {
 68	      if(val.second !=1) {
 69		matched = false;
 70		break;
 71	      }
 72	    }
 73	    else if(val.second!=0) {
 74	      matched = false;
 75	      break;
 76	    }
 77	  }
 78	  if(matched)
 79	    _nomega->fill();
 80	}
 81      }
 82    }
 83
 84
 85    /// Normalise histograms etc., after the run
 86    void finalize() {
 87      for(unsigned int ix=1;ix<3;++ix) {
 88	double sigma = 0., error = 0.;
 89	if(ix==1) {
 90	  sigma = _n3pi->val();
 91	  error = _n3pi->err();
 92	}
 93	else if(ix==2) {
 94	  sigma = _nomega->val();
 95	  error = _nomega->err();
 96	}
 97	sigma *= crossSection()/ sumOfWeights() /nanobarn;
 98	error *= crossSection()/ sumOfWeights() /nanobarn; 
 99	Scatter2D temphisto(refData(ix, 1, 1));
100	Scatter2DPtr mult;
101	book(mult, ix, 1, 1);
102	for (size_t b = 0; b < temphisto.numPoints(); b++) {
103	  const double x  = temphisto.point(b).x();
104	  pair<double,double> ex = temphisto.point(b).xErrs();
105	  pair<double,double> ex2 = ex;
106	  if(ex2.first ==0.) ex2. first=0.0001;
107	  if(ex2.second==0.) ex2.second=0.0001;
108	  if (inRange(sqrtS()/MeV, x-ex2.first, x+ex2.second)) {
109	    mult->addPoint(x, sigma, ex, make_pair(error,error));
110	  }
111	  else {
112	    mult->addPoint(x, 0., ex, make_pair(0.,.0));
113	  }
114	}
115      }
116    }
117
118    //@}
119
120
121    /// @name Histograms
122    //@{
123    CounterPtr _n3pi,_nomega;
124    //@}
125
126
127  };
128
129
130  // The hook for the plugin system
131  RIVET_DECLARE_PLUGIN(DM2_1992_I339265);
132
133
134}