Rivet analyses

title: OPAL_1994_I372772

Measurement of the production rates of charged hadrons in $e^+e^-$ annihilation at the $Z^0$

Experiment: OPAL (LEP 1)

Inspire ID: 372772

Status: VALIDATED

Authors: - Peter Richardson

References: - Z.Phys.C63:181-196,1994

Beams: e+ e-

Beam energies: (45.6, 45.6)GeV

Run details: - Hadronic Z decay events generated on the Z pole ($\sqrt{s} = 91.2$ GeV)

The inclusive production rates of $\pi^\pm$, $K^\pm$ and $p\bar{p}$ in $Z^0$ decays measured using the OPAL detector at LEP. Only the differential cross sections are currently implemented.

Source code:OPAL_1994_I372772.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/ChargedFinalState.hh"

namespace Rivet {

/// @brief OPAL charged particle fragmentation functions /// /// @author Peter Richardson class OPAL_1994_I372772 : public Analysis { public:

RIVET_DEFAULT_ANALYSIS_CTOR(OPAL_1994_I372772);


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

void analyze(const Event& e) {

  // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
  const FinalState& fs = apply<FinalState>(e, "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>(e, "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) {
      _histXpPiPlus->fill(p.p3().mod());
    }
    else if (id == PID::KPLUS) {
      _histXpKPlus->fill(p.p3().mod());
    }
    else if (id == PID::PROTON) {
      _histXpProton->fill(p.p3().mod());
    }
  }
}


void init() {
  // Projections
  declare(Beam(), "Beams");
  declare(ChargedFinalState(), "FS");

  book(_histXpPiPlus, 1, 1, 1);
  book(_histXpKPlus, 2, 1, 1);
  book(_histXpProton, 3, 1, 1);
}


/// Finalize
void finalize() {
  scale(_histXpPiPlus, 1. / sumOfWeights());
  scale(_histXpKPlus, 1. / sumOfWeights());
  scale(_histXpProton, 1. / sumOfWeights());
}

/// @}

private:

Histo1DPtr _histXpPiPlus;
Histo1DPtr _histXpKPlus;
Histo1DPtr _histXpProton;

};

RIVET_DECLARE_ALIASED_PLUGIN(OPAL_1994_I372772, OPAL_1994_S2927284);

} ```

Aliases: - OPAL_1994_S2927284