rivet is hosted by Hepforge, IPPP Durham

## Rivet analyses reference

### OPAL_1997_S3396100

Strange baryon production in $Z$ hadronic decays at OPAL
Experiment: OPAL (LEP 1)
Inspire ID: 421978
Status: VALIDATED
Authors:
• Peter Richardson
References:
• Z. Phys. C, 73, 569--586 (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)

Measurement of the $\Xi^-$, $\Lambda^0$, $\Sigma^+(1385)$, $\Sigma^-(1385)$, $\Xi^0(1530)$ and $\Lambda^0(1520)$ scaled momentum distributions by OPAL at LEP 1. The paper also has the production cross-sections of these particles, but that is not implemented in Rivet.

Source code: OPAL_1997_S3396100.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 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/Beam.hh" #include "Rivet/Projections/FinalState.hh" #include "Rivet/Projections/ChargedFinalState.hh" #include "Rivet/Projections/UnstableParticles.hh" namespace Rivet { /// @brief OPAL strange baryon paper /// @author Peter Richardson class OPAL_1997_S3396100 : public Analysis { public: /// Constructor OPAL_1997_S3396100() : Analysis("OPAL_1997_S3396100") {} /// @name Analysis methods //@{ void init() { declare(Beam(), "Beams"); declare(ChargedFinalState(), "FS"); declare(UnstableParticles(), "UFS"); book(_histXpLambda , 1, 1, 1); book(_histXiLambda , 2, 1, 1); book(_histXpXiMinus , 3, 1, 1); book(_histXiXiMinus , 4, 1, 1); book(_histXpSigma1385Plus , 5, 1, 1); book(_histXiSigma1385Plus , 6, 1, 1); book(_histXpSigma1385Minus , 7, 1, 1); book(_histXiSigma1385Minus , 8, 1, 1); book(_histXpXi1530 , 9, 1, 1); book(_histXiXi1530 ,10, 1, 1); book(_histXpLambda1520 ,11, 1, 1); book(_histXiLambda1520 ,12, 1, 1); } void analyze(const Event& e) { // First, veto on leptonic events by requiring at least 4 charged FS particles const FinalState& fs = apply(e, "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(e, "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(e, "UFS"); for (const Particle& p : ufs.particles()) { const int id = p.abspid(); double xp = p.p3().mod()/meanBeamMom; double xi = -log(xp); switch (id) { case 3312: _histXpXiMinus->fill(xp); _histXiXiMinus->fill(xi); break; case 3224: _histXpSigma1385Plus->fill(xp); _histXiSigma1385Plus->fill(xi); break; case 3114: _histXpSigma1385Minus->fill(xp); _histXiSigma1385Minus->fill(xi); break; case 3122: _histXpLambda->fill(xp); _histXiLambda->fill(xi); break; case 3324: _histXpXi1530->fill(xp); _histXiXi1530->fill(xi); break; case 3124: _histXpLambda1520->fill(xp); _histXiLambda1520->fill(xi); break; } } } /// Finalize void finalize() { double fact=1./sumOfWeights(); scale(_histXpLambda , fact); scale(_histXiLambda , fact); scale(_histXpXiMinus , fact); scale(_histXiXiMinus , fact); scale(_histXpSigma1385Plus , fact); scale(_histXiSigma1385Plus , fact); scale(_histXpSigma1385Minus, fact); scale(_histXiSigma1385Minus, fact); scale(_histXpXi1530 , fact); scale(_histXiXi1530 , fact); scale(_histXpLambda1520 , fact); scale(_histXiLambda1520 , fact); } //@} private: Histo1DPtr _histXpLambda ; Histo1DPtr _histXiLambda ; Histo1DPtr _histXpXiMinus ; Histo1DPtr _histXiXiMinus ; Histo1DPtr _histXpSigma1385Plus ; Histo1DPtr _histXiSigma1385Plus ; Histo1DPtr _histXpSigma1385Minus; Histo1DPtr _histXiSigma1385Minus; Histo1DPtr _histXpXi1530 ; Histo1DPtr _histXiXi1530 ; Histo1DPtr _histXpLambda1520 ; Histo1DPtr _histXiLambda1520 ; //@} }; // The hook for the plugin system DECLARE_RIVET_PLUGIN(OPAL_1997_S3396100); }