Rivet analyses

title: MARKI_1975_I100733

Measurement of $R$ and the hadronic cross section for energies between 2.4 and 6.9 GeV

Experiment: MARKI (Spear)

Inspire ID: 100733

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 $R$ and the hadronic cross section for energies between 2.4 and 6.9 GeV. The charged hadron spectum at 3, 4.8 and 7.4 GeV is also measured. The muonic cross sections is also outputted to the yoda file so that ratio $R$ can be recalcuated if runs are combined.

Source code:MARKI_1975_I100733.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief R measurement class MARKI_1975_I100733 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(MARKI_1975_I100733);


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

/// Book histograms and initialise projections before the run
void init() {

  declare(FinalState(), "FS");
  // Book histograms
  book(_h["hadrons0"], 1, 1, 1);
  book(_h["hadrons1"], "/TMP/sigma_hadrons", refData<YODA::BinnedEstimate<string>>(2, 1, 1));
  book(_h["muons"], "/TMP/sigma_muons", refData<YODA::BinnedEstimate<string>>(2, 1, 1));
  for (size_t ix = 0; ix < 2; ++ix) {
    for (const string& en : _h["hadrons" + toString(ix)].binning().edges<0>()) {
      const size_t idx = en.find("-");
      if (idx != std::string::npos) {
        const double emin = std::stod(en.substr(0, idx));
        const double emax = std::stod(en.substr(idx + 1, string::npos));
        if (inRange(sqrtS() / GeV, emin, emax)) {
          _sqs[ix] = en;
          break;
        }
      }
      else {
        const double eval = stod(en) * GeV;
        if (isCompatibleWithSqrtS(eval)) {
          _sqs[ix] = en;
          break;
        }
      }
    }
  }
  raiseBeamErrorIf(_sqs[0].empty() && _sqs[1].empty());
  if (_sqs[1] == "3.0"s) {
    book(_h[_sqs[1] + "charged"], 3, 1, 1);
  }
  else if (_sqs[1] == "4.8"s) {
    book(_h[_sqs[1] + "charged"], 3, 1, 2);
  }
  else if (_sqs[1] == "7.4"s) {
    book(_h[_sqs[1] + "charged"], 3, 1, 3);
  }
}


/// 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]) {
    _h["muons"]->fill(_sqs[1]); // mu+mu- + photons
  }
  // everything else
  else {
    _h["hadrons0"]->fill(_sqs[0]);
    _h["hadrons1"]->fill(_sqs[1]);
    if (_sqs[1] == "3.0"s || _sqs[1] == "4.8"s || _sqs[1] == "7.4"s) {
      if (_edges.empty()) _edges = _h[_sqs[1] + "charged"]->xEdges();
      for (const Particle& p : fs.particles()) {
        if (PID::isCharged(p.pid())) {
          double x = 2. * p.p3().mod() / sqrtS();
          const size_t idx = _axis.index(x);
          if (idx && idx <= _edges.size()) _h[_sqs[1] + "charged"]->fill(_edges[idx - 1]);
        }
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  const double sf = crossSection() / sumOfWeights() / nanobarn;
  for (auto& item : _h) {
    if (item.first.find("charged") != string::npos) {
      scale(item.second, crossSection() / sumOfWeights() / microbarn * sqr(sqrtS()));
      for (auto& b : item.second->bins()) {
        b.scaleW(1. / _axis.width(b.index()));
      }
      continue;
    }
    scale(item.second, sf);
  }
  BinnedEstimatePtr<string> mult;
  book(mult, 2, 1, 1);
  divide(_h["hadrons1"], _h["muons"], mult);
}

/// @}


/// @name Histograms
/// @{
map<string, BinnedHistoPtr<string>> _h;
vector<string> _edges;
string _sqs[2];
YODA::Axis<double> _axis{0.,   0.10, 0.12, 0.14, 0.16, 0.18, 0.20, 0.22, 0.24, 0.26, 0.28, 0.30, 0.32,
                         0.34, 0.36, 0.38, 0.40, 0.44, 0.48, 0.52, 0.56, 0.64, 0.72, 0.80, 0.88};
/// @}

};

RIVET_DECLARE_PLUGIN(MARKI_1975_I100733);

} ```