Rivet analyses

title: ALEPH_1995_I382179

Inclusive pi+-, K+- and (p, anti-p) differential cross-sections at the Z resonance

Experiment: ALEPH (LEP)

Inspire ID: 382179

Status: VALIDATED

Authors: - Simone Amoroso

References: - Z.Phys. C66 (1995) 355-366 - DOI: 10.1007/BF01556360

Beams: e+ e-

Beam energies: (45.6, 45.6)GeV

Run details: - e+e- production at the Z-peak with hadronic decays

Inclusive spectra of pions, Kaons, protons and antiprotons in hadronic decays of the Z0 measured as a function of z.

Source code:ALEPH_1995_I382179.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/ChargedFinalState.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief ALEPH pi+-, K+-, p and pbar differential cross-sections at the Z peak class ALEPH_1995_I382179 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ALEPH_1995_I382179);


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

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

  // Initialise and register projections
  declare(Beam(), "Beams");
  declare(ChargedFinalState(), "FS");

  // Book histograms
  book(_histXpPion, 1, 1, 1);
  book(_histXpKaon, 2, 1, 1);
  book(_histXpProton, 3, 1, 1);
}


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

  // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
  const FinalState& fs = apply<FinalState>(event, "FS");
  if (fs.particles().size() < 2) {
    MSG_DEBUG("Failed ncharged cut");
    vetoEvent;
  }
  MSG_DEBUG("Passed ncharged 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);

  for (const Particle& p : fs.particles()) {
    int id = p.abspid();
    // charged pions
    if (id == PID::PIPLUS || id == PID::PIMINUS) {
      _histXpPion->fill(p.p3().mod() / meanBeamMom);
    }
    else if (id == PID::KPLUS || id == PID::KMINUS) {
      _histXpKaon->fill(p.p3().mod() / meanBeamMom);
    }
    else if (id == PID::PROTON || id == PID::ANTIPROTON) {
      _histXpProton->fill(p.p3().mod() / meanBeamMom);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_histXpPion, 1. / sumOfWeights());
  scale(_histXpKaon, 1. / sumOfWeights());
  scale(_histXpProton, 1. / sumOfWeights());
}

/// @}

private:

/// @name Histograms
Histo1DPtr _histXpPion;
Histo1DPtr _histXpKaon;
Histo1DPtr _histXpProton;

};

RIVET_DECLARE_PLUGIN(ALEPH_1995_I382179);

} ```