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## Rivet analyses reference

### OPAL_1997_I421977

$\Sigma^{\pm}$ baryon production in $Z$ hadronic decays at OPAL
Experiment: OPAL (LEP)
Inspire ID: 421977
Status: VALIDATED
Authors:
• Peter Richardson
References:
• Z.Phys. C73 (1997) 587-600, 1997
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)

Spectra for the production of the $\Sigma^\pm$ baryons at LEP I measured by OPAL.

Source code: OPAL_1997_I421977.cc
  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/Beam.hh" #include "Rivet/Projections/ChargedFinalState.hh" #include "Rivet/Projections/UnstableParticles.hh" namespace Rivet { /// @brief OPAL strange baryon paper /// @author Peter Richardson class OPAL_1997_I421977 : public Analysis { public: /// Constructor DEFAULT_RIVET_ANALYSIS_CTOR(OPAL_1997_I421977); /// @name Analysis methods //@{ /// Book histograms and initialise projections before the run void init() { declare(Beam(), "Beams"); declare(ChargedFinalState(), "FS"); declare(UnstableParticles(), "UFS"); // Book histograms book(_h_plus, 1, 1, 1); book(_h_minus, 2, 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(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(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(event, "UFS"); for (const Particle& p : ufs.particles()) { const int id = p.abspid(); double xE = p.E()/meanBeamMom; if(id==3222) _h_plus ->fill(xE); else if(id==3112) _h_minus->fill(xE); } } /// Normalise histograms etc., after the run void finalize() { double fact=1./sumOfWeights(); scale(_h_plus , fact); scale(_h_minus, fact); } //@} /// @name Histograms //@{ Histo1DPtr _h_plus,_h_minus; //@} }; // The hook for the plugin system DECLARE_RIVET_PLUGIN(OPAL_1997_I421977); }