Rivet analyses

title: CRYSTAL_BALL_1986_I238081

Measurement of $R$ and $D^*$ production for energies between 3.67 and 4.5 GeV.

Experiment: CRYSTAL_BALL (Spear)

Inspire ID: 238081

Status: VALIDATED

Authors: - Peter Richardson

References: - https://doi.org/10.17182/hepdata.18759

Beams: e- e+

Beam energies: ANY

Run details: - e+ e- to hadrons and e+ e- to mu+ mu- (for normalization)

Measurement of $R$ in $e^+e^-$ collisions by the Crystal Ball experiment for energies between 3.67 and 4.5 GeV. The cross section for $D^*$ production is also measured. 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:CRYSTAL_BALL_1986_I238081.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief e+e- > hadrons class CRYSTAL_BALL_1986_I238081 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CRYSTAL_BALL_1986_I238081);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");
  declare(UnstableParticles(), "UFS");

  // Book histograms
  book(_c_hadrons, "/TMP/sigma_hadrons", refData<YODA::BinnedEstimate<string>>(1, 1, 1));
  book(_c_muons, "/TMP/sigma_muons", refData<YODA::BinnedEstimate<string>>(1, 1, 1));
  book(_c_D_star, "/TMP/sigma_D_star", refData(2, 1, 1));

  for (const string& en : _c_hadrons.binning().edges<0>()) {
    if (isCompatibleWithSqrtS(stod(en) * GeV, 1e-3)) {
      _sqs = en;
      break;
    }
  }
  raiseBeamErrorIf(_sqs.empty() and !inRange(sqrtS() / GeV, 3.87, 4.5));
}


/// 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;
  }
  if (nCount[-13] == 1 && nCount[13] == 1 && ntotal == 2 + nCount[22]) {
    // mu+mu- + photons
    _c_muons->fill(_sqs);
  }
  else
    _c_hadrons->fill(_sqs); // everything else
  const FinalState& ufs = apply<UnstableParticles>(event, "UFS");
  bool found = false;
  for (const Particle& p : ufs.particles()) {
    if (p.abspid() != 413 && p.abspid() != 423) continue;
    bool fs = true;
    for (const Particle& child : p.children()) {
      if (child.pid() == p.pid()) {
        fs = false;
        break;
      }
    }
    if (fs) {
      found = true;
      break;
    }
  }
  if (found) _c_D_star->fill(sqrtS());
}


/// Normalise histograms etc., after the run
void finalize() {
  // R
  BinnedEstimatePtr<string> tmp;
  book(tmp, 1, 1, 1);
  divide(_c_hadrons, _c_muons, tmp);
  double fact = crossSection() / sumOfWeights() / nanobarn;
  scale(_c_D_star, fact);
  Estimate1DPtr tmp2;
  book(tmp2, 2, 1, 1);
  barchart(_c_D_star, tmp2);
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _c_hadrons, _c_muons;
Histo1DPtr _c_D_star;
string _sqs = "";
/// @}

};

RIVET_DECLARE_PLUGIN(CRYSTAL_BALL_1986_I238081); } ```