Rivet analyses

title: GAMMAGAMMA_1975_I100016

Measurement of $R$ and the hadronic cross section for energies between 1.91 and 2.97 GeV

Experiment: GAMMAGAMMA (ADONE)

Inspire ID: 100016

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B58 (1975) 481-483, 1975

Beams: e- e+

Beam energies: ANY

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 the GAMMA-GAMMA group for energies between 1.91 and 2.97 GeV. The muonic cross section is also outputted to the yoda file so that ratio $R$ can be recalcuated if runs are combined.

Source code:GAMMAGAMMA_1975_I100016.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief e+e- R class GAMMAGAMMA_1975_I100016 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(GAMMAGAMMA_1975_I100016);


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

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

  // Book histograms
  book(_c_hadrons, "/TMP/sigma_hadrons", refData(1, 1, 2));
  book(_c_muons, "/TMP/sigma_muons", refData(1, 1, 2));
}


/// 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]) _c_muons->fill(sqrtS() / GeV);
  // everything else
  else
    _c_hadrons->fill(sqrtS() / GeV);
}


/// Normalise histograms etc., after the run
void finalize() {
  Estimate1DPtr mult;
  book(mult, 1, 1, 2);
  divide(_c_hadrons, _c_muons, mult);
  double fact = crossSection() / sumOfWeights() / nanobarn;
  scale(_c_hadrons, fact);
  book(mult, 1, 1, 1);
  barchart(_c_hadrons, mult);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _c_hadrons, _c_muons;
/// @}

};

RIVET_DECLARE_PLUGIN(GAMMAGAMMA_1975_I100016);

} ```