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MARKII_1979_I143939

Measurement of $R$ and $D\bar{D}$ cross section between 3.67 and 3.872 GeV
Experiment: MARKII (SPEAR)
Inspire ID: 143939
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Schindler, R.H. PhD Thesis, 1979
Beams: e- e+
Beam energies: (1.8, 1.8); (1.8, 1.8); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9) GeV
Run details:
  • e+ e- to hadrons and e+ e- to mu+ mu- (for normalization)

Measurement of $R$ and the $D\bar{D}$ cross section in $e^+e^-$ collisions between 3.67 and 3.872 GeV The individual hadronic and muonic cross sections are also outputted to the yoda file so that ratio $R$ can be recalcuated if runs are combined.

Source code: MARKII_1979_I143939.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 MARKII_1979_I143939 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(MARKII_1979_I143939);
 15
 16
 17    /// @name Analysis methods
 18    /// @{
 19
 20    /// Book histograms and initialise projections before the run
 21    void init() {
 22      declare(FinalState(), "FS");
 23      declare(UnstableParticles(), "UFS");
 24      book(_c_hadrons, "/TMP/sigma_hadrons", refData<YODA::BinnedEstimate<string>>(2,1,1));
 25      book(_c_muons,   "/TMP/sigma_muons"  , refData<YODA::BinnedEstimate<string>>(2,1,1));
 26      book(_c_DD, 3, 1, 1);
 27      for (const string& en : _c_hadrons.binning().edges<0>()) {
 28        double end = std::stod(en)*GeV;
 29        if(isCompatibleWithSqrtS(end)) {
 30          _ecms = en;
 31          break;
 32        }
 33      }
 34      if(_ecms.empty()) MSG_ERROR("Beam energy incompatible with analysis.");
 35    }
 36
 37    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
 38      for (const Particle &child : p.children()) {
 39	if(child.children().empty()) {
 40	  nRes[child.pid()]-=1;
 41	  --ncount;
 42	}
 43	else
 44	  findChildren(child,nRes,ncount);
 45      }
 46    }
 47
 48    /// Perform the per-event analysis
 49    void analyze(const Event& event) {
 50      const FinalState& fs = apply<FinalState>(event, "FS");
 51      // total hadronic and muonic cross sections
 52      map<long,int> nCount;
 53      int ntotal(0);
 54      for (const Particle& p : fs.particles()) {
 55	nCount[p.pid()] += 1;
 56	++ntotal;
 57      }
 58      // mu+mu- + photons
 59      if(nCount[-13]==1 and nCount[13]==1 &&
 60	 ntotal==2+nCount[22])
 61	_c_muons->fill(_ecms);
 62      // everything else
 63      else
 64	_c_hadrons->fill(_ecms);
 65      // identified final state with D mesons
 66      const FinalState& ufs = apply<UnstableParticles>(event, "UFS");
 67      for(unsigned int ix=0;ix<ufs.particles().size();++ix) {
 68	bool matched = false;
 69       	const Particle& p1 = ufs.particles()[ix];
 70       	int id1 = abs(p1.pid());
 71       	if(id1 != 411 && id1 != 421) continue;
 72      	// check fs
 73      	bool fs = true;
 74      	for (const Particle & child : p1.children()) {
 75      	  if(child.pid()==p1.pid()) {
 76      	    fs = false;
 77      	    break;
 78      	  }
 79      	}
 80      	if(!fs) continue;
 81      	// find the children
 82      	map<long,int> nRes = nCount;
 83      	int ncount = ntotal;
 84      	findChildren(p1,nRes,ncount);
 85      	// loop over the other fs particles
 86       	for(unsigned int iy=ix+1;iy<ufs.particles().size();++iy) {
 87       	  const Particle& p2 = ufs.particles()[iy];
 88       	  fs = true;
 89       	  for (const Particle & child : p2.children()) {
 90       	    if(child.pid()==p2.pid()) {
 91       	      fs = false;
 92       	      break;
 93       	    }
 94       	  }
 95       	  if(!fs) continue;
 96       	  if(p2.pid()/abs(p2.pid())==p1.pid()/abs(p1.pid())) continue;
 97       	  int id2 = abs(p2.pid());
 98       	  if(id2 != 411 && id2 != 421) continue;
 99      	  if(!p2.parents().empty() && p2.parents()[0].pid()==p1.pid())
100      	    continue;
101      	  map<long,int> nRes2 = nRes;
102      	  int ncount2 = ncount;
103      	  findChildren(p2,nRes2,ncount2);
104      	  if(ncount2!=0) continue;
105	  matched=true;
106	  for(auto const & val : nRes2) {
107	    if(val.second!=0) {
108	      matched = false;
109	      break;
110	    }
111	  }
112	  if(matched) {
113	    _c_DD  ->fill(_ecms);
114	    break;
115	  }
116	}
117	if(matched) break;
118      }
119    }
120
121
122    /// Normalise histograms etc., after the run
123    void finalize() {
124      double fact = crossSection()/ sumOfWeights() /nanobarn;
125      BinnedEstimatePtr<string> mult;
126      book(mult, 2, 1, 1);
127      divide(_c_hadrons,_c_muons,mult);
128      scale(_c_DD,fact);
129    }
130
131    /// @}
132
133
134    /// @name Histograms
135    /// @{
136    BinnedHistoPtr<string> _c_hadrons, _c_muons, _c_DD;
137    string _ecms;
138    /// @}
139
140
141  };
142
143
144  RIVET_DECLARE_PLUGIN(MARKII_1979_I143939);
145
146
147}