Rivet analyses

title: MC_IDENTIFIED

MC testing analysis for identified particle distributions

Experiment: ()

Status: VALIDATED

Authors: - Andy Buckley

References: none listed

Beams: * *

Beam energies: ANY

Run details: - Any!

Plotting of distributions of PID codes (all/stable/unstable) and ID-specific distributions such as the $|\eta|$ of $K$, $\pi$ and $\Lambda$ mesons.

Source code:MC_IDENTIFIED.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// Generic analysis looking at various distributions of final state particles /// /// @todo Rename as MC_HADRONS? class MC_IDENTIFIED : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(MC_IDENTIFIED);


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

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

  // Projections
  const FinalState cnfs(Cuts::abseta < 5.0 && Cuts::pT > 500 * MeV);
  declare(cnfs, "FS");
  declare(UnstableParticles(Cuts::abseta < 5.0 && Cuts::pT > 500 * MeV), "UFS");

  // Histograms
  // @todo Choose E/pT ranged based on input energies... can't do anything about kin. cuts, though

  book(_histStablePIDs, "MultsStablePIDs", 3335, -0.5, 3334.5);
  book(_histDecayedPIDs, "MultsDecayedPIDs", 3335, -0.5, 3334.5);
  book(_histAllPIDs, "MultsAllPIDs", 3335, -0.5, 3334.5);

  book(_histEtaPi, "EtaPi", 25, 0, 5);
  book(_histEtaK, "EtaK", 25, 0, 5);
  book(_histEtaLambda, "EtaLambda", 25, 0, 5);
}


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

  // Unphysical (debug) plotting of all PIDs in the event, physical or otherwise
  for (ConstGenParticlePtr gp : HepMCUtils::particles(event.genEvent())) {
    _histAllPIDs->fill(abs(gp->pdg_id()));
  }

  // Charged + neutral final state PIDs
  const FinalState& cnfs = apply<FinalState>(event, "FS");
  for (const Particle& p : cnfs.particles()) {
    _histStablePIDs->fill(p.abspid());
  }

  // Unstable PIDs and identified particle eta spectra
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles()) {
    _histDecayedPIDs->fill(p.pid());
    const double eta_abs = p.abseta();
    const PdgId pid = p.abspid(); //if (PID::isMeson(pid) && PID::hasStrange()) {
    if (pid == 211 || pid == 111)
      _histEtaPi->fill(eta_abs);
    else if (pid == 321 || pid == 130 || pid == 310)
      _histEtaK->fill(eta_abs);
    else if (pid == 3122)
      _histEtaLambda->fill(eta_abs);
  }
}


/// Finalize
void finalize() {
  scale(_histStablePIDs, 1 / sumOfWeights());
  scale(_histDecayedPIDs, 1 / sumOfWeights());
  scale(_histAllPIDs, 1 / sumOfWeights());
  scale(_histEtaPi, 1 / sumOfWeights());
  scale(_histEtaK, 1 / sumOfWeights());
  scale(_histEtaLambda, 1 / sumOfWeights());
}

/// @}

private:

/// @name Histograms
/// @{
Histo1DPtr _histStablePIDs, _histDecayedPIDs, _histAllPIDs;
Histo1DPtr _histEtaPi, _histEtaK, _histEtaLambda;
/// @}

};

RIVET_DECLARE_PLUGIN(MC_IDENTIFIED);

} ```