Rivet analyses

title: DELPHI_2000_I524694

$\Sigma^-$ and $\Lambda(1520)$ production at the $Z^0$ pole from DELPHI

Experiment: DELPHI (LEP)

Inspire ID: 524694

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B475 (2000) 429-447, 2000

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)

Measurement of the $\Sigma^-$ and $\Lambda^0(1520)$ scaled momentum distributions by DELPHI at LEP 1

Source code:DELPHI_2000_I524694.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Sigma- and Lambda(1520) ar Z pole class DELPHI_2000_I524694 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(DELPHI_2000_I524694);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(Beam(), "Beams");
  declare(UnstableParticles(), "UFS");
  book(_histXpSigma, 1, 1, 1);
  book(_histXpLambda, 3, 1, 1);
}


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


  // Get event weight for histo filling

  // 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;

  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles()) {
    const int id = p.abspid();
    double xp = p.p3().mod() / meanBeamMom;
    switch (id) {
      case 3112: _histXpSigma->fill(xp); break;
      case 102134: _histXpLambda->fill(xp); break;
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  double fact = 1. / sumOfWeights();
  scale(_histXpSigma, fact);
  scale(_histXpLambda, fact);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _histXpSigma;
Histo1DPtr _histXpLambda;
/// @}

};

RIVET_DECLARE_PLUGIN(DELPHI_2000_I524694);

} ```