Rivet analyses

title: PLUTO_1977_I118873

$K^0$ spectra at $3.63$, $4.03$ and $4.5$ GeV

Experiment: PLUTO (DORIS)

Inspire ID: 118873

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B104 (1981) 79-83, 1981

Beams: e- e+

Beam energies: ANY

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

The spectra for $K^0$ production at $3.63$, $4.03$ and $4.5$ GeV measured by the PLUTO experiment together with the cross section for $K^0_S$ production for a range of energies. The energy dependent cross section is not included as it is implemented in PLUTO_1981_I165122.

Source code:PLUTO_1977_I118873.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Kaon spectra at 3.63, 4.03 and 4.5 GeV class PLUTO_1977_I118873 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(PLUTO_1977_I118873);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(Beam(), "Beams");
  declare(UnstableParticles(Cuts::pid == PID::K0S), "UFS");
  book(_h_sigma, 1, 1, 1);
  for (const string& en : _h_sigma.binning().edges<0>()) {
    const size_t idx = en.find("-");
    if (idx != 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)) {
        _edge = en;
        break;
      }
    }
    else {
      const double eval = std::stod(en);
      if (isCompatibleWithSqrtS(eval)) {
        _edge = en;
        break;
      }
    }
  }
  size_t ih = 1;
  for (const double eval : {3.63, 4.03, 4.5}) {
    const string label = toString(eval / MeV);
    if (isCompatibleWithSqrtS(eval)) _sqs = label;
    book(_h[label], ++ih, 1, 1);
  }
  raiseBeamErrorIf(_edge.empty() && _sqs.empty());
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  // Get beams and average beam momentum
  const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
  const double meanBeamMom = 0.5 * (beams.first.p3().mod() + beams.second.p3().mod());
  MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
  // unstable particles
  for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles()) {
    _h_sigma->fill(_edge);
    const double xp = p.E() / meanBeamMom;
    const double beta = p.p3().mod() / p.E();
    if (!_sqs.empty()) _h[_sqs]->fill(xp, 1.0 / beta);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  const double sf = crossSection() / nanobarn / sumOfWeights();
  scale(_h, sqr(sqrtS()) * sf); //< Undefined when merging
  scale(_h_sigma, sf);
}

/// @}


/// @name Histograms
/// @{
map<string, Histo1DPtr> _h;
BinnedHistoPtr<string> _h_sigma;
string _sqs = "", _edge = "";
/// @}

};

RIVET_DECLARE_PLUGIN(PLUTO_1977_I118873);

} ```