Rivet analyses

title: TPC_1984_I205869

$K^{*0}$ and $K^0$ spectra at 29 GeV

Experiment: TPC (PEP)

Inspire ID: 205869

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 53 (1984) 2378, 1984

Beams: e+ e-

Beam energies: (14.5, 14.5)GeV

Run details: - e+e- to hadrons at 29 GeV

Measurement of the $K^{*0}$ and $K^0$ spectra at 29 GeV by the TPC experiment.

Source code:TPC_1984_I205869.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/ChargedFinalState.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief K*0 and K0 spectra at 29 GeV class TPC_1984_I205869 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(TPC_1984_I205869);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(Beam(), "Beams");
  declare(ChargedFinalState(), "FS");
  declare(UnstableParticles(), "UFS");
  book(_histKstar, 3, 1, 1);
  book(_histK, 4, 1, 1);
}


/// Perform the per-event analysis
void analyze(const Event& event) {

  // First, veto on leptonic events by requiring at least 4 charged FS particles
  const FinalState& fs = apply<FinalState>(event, "FS");
  const size_t numParticles = fs.particles().size();

  // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
  if (numParticles < 2) {
    MSG_DEBUG("Failed leptonic event cut");
    vetoEvent;
  }
  MSG_DEBUG("Passed leptonic event cut");

  // Get beams and average beam momentum
  const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
  const double meanBeamMom = (beams.first.p3().mod() + beams.second.p3().mod()) / 2.0;
  MSG_DEBUG("Avg beam momentum = " << meanBeamMom);

  // Final state of unstable particles to get particle spectra
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");

  for (const Particle& p : ufs.particles()) {
    const int id = p.abspid();
    double xE = p.E() / meanBeamMom;
    switch (id) {
      case 313: // Photons
        _histKstar->fill(xE);
        break;
      case 130:
      case 310: _histK->fill(xE); break;
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_histKstar, 1. / sumOfWeights());
  scale(_histK, 1. / sumOfWeights());
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _histKstar;
Histo1DPtr _histK;
/// @}

};

RIVET_DECLARE_PLUGIN(TPC_1984_I205869);

} ```