Rivet analyses

title: KEDR_2019_I1673357

Measurement of $R$ between 1.84 and 3.72 GeV

Experiment: KEDR (VEPP-4M)

Inspire ID: 1673357

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B788 (2019) 42-51

Beams: e+ e-

Beam energies: ANY

Run details: - e+e- to hadrons and muon so the ratio can be computed

Measurement of $R$ for centre-of-mass energies between 1.84 and 3.72 GeV by the KEDR experiment.

Source code:KEDR_2019_I1673357.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Measurement of R class KEDR_2019_I1673357 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(KEDR_2019_I1673357);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");
  declare(UnstableParticles(Cuts::pid == 443 or Cuts::pid == 100443 or Cuts::pid == 30443), "UFS");

  // Book histograms
  book(_c_hadrons[0], "/TMP/sigma_hadrons_1", refData(1, 1, 1));
  book(_c_hadrons[1], "/TMP/sigma_hadrons_2", refData(1, 1, 2));
  book(_c_muons, "/TMP/sigma_muons", refData(1, 1, 1));
}


/// 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() / MeV);
  // everything else
  else {
    const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
    if (ufs.particles().empty()) _c_hadrons[0]->fill(sqrtS() / MeV);
    _c_hadrons[1]->fill(sqrtS() / MeV);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (unsigned int ix = 0; ix < 2; ++ix) {
    Estimate1DPtr mult;
    book(mult, 1, 1, 1 + ix);
    divide(_c_hadrons[ix], _c_muons, mult);
  }
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _c_hadrons[2], _c_muons;
/// @}

};

RIVET_DECLARE_PLUGIN(KEDR_2019_I1673357);

} ```