Rivet analyses

title: BESII_2006_I735496

Measurement of $R$ for energies between 3.65 and 3.872 GeV

Experiment: BESII (BEPC)

Inspire ID: 735496

Status: VALIDATED NOHEPDATA SINGLEWEIGHT

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 97 (2006) 262001

Beams: e+ e-

Beam energies: (1.8, 1.8); (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); (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); (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 hadronic cross section in $e^+e^-$ collisions by BESII for energies between 3.65 and 3.872, in the vicinity of the $\psi(3770)$.

Source code:BESII_2006_I735496.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Measurement of R 3.65 and 3.872 GeV class BESII_2006_I735496 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESII_2006_I735496);


/// @name Analysis methods
/// @{

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(UnstableParticles(Cuts::abspid == 100443 || Cuts::abspid == 30443), "UFS");
  declare(FinalState(), "FS");
  // Book histograms
  for (size_t ix = 0; ix < 2; ++ix) {
    book(_sigma_hadrons[ix], "/TMP/sigma_hadrons_" + toString(ix + 1),
         refData<YODA::BinnedEstimate<string>>(1, 1, 1 + ix));
  }
  book(_sigma_muons, "/TMP/sigma_muons", refData<YODA::BinnedEstimate<string>>(1, 1, 1));

  for (const string& en : _sigma_muons.binning().edges<0>()) {
    const double eval = stod(en) * GeV;
    if (isCompatibleWithSqrtS(eval)) {
      _sqs = en;
      break;
    }
  }
  raiseBeamErrorIf(_sqs.empty());
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  const FinalState& fs = apply<FinalState>(event, "FS");

  map<long, int> nCount;
  int ntotal(0);
  for (const Particle& p : fs.particles()) {
    nCount[p.pid()] += 1;
    ++ntotal;
  }
  // mu+mu- + photons
  if (nCount[-13] == 1 and nCount[13] == 1 && ntotal == 2 + nCount[22]) _sigma_muons->fill(_sqs);
  // everything else
  else {
    _sigma_hadrons[1]->fill(_sqs);
    Particles psi = apply<UnstableParticles>(event, "UFS").particles();
    if (psi.empty()) {
      _sigma_hadrons[0]->fill(_sqs);
    }
    else {
      bool psi3770 = false;
      for (const Particle& p : psi) psi3770 |= p.pid() == 30443;
      if (psi3770) _sigma_hadrons[0]->fill(_sqs);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (size_t ix = 0; ix < 2; ++ix) {
    BinnedEstimatePtr<string> R;
    book(R, 1, 1, 1 + ix);
    divide(_sigma_hadrons[ix], _sigma_muons, R);
  }
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _sigma_hadrons[2], _sigma_muons;
string _sqs = "";
/// @}

};

RIVET_DECLARE_PLUGIN(BESII_2006_I735496);

} ```