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## Rivet analyses reference

### OPAL_2003_I599181

Inclusive analysis of the b quark fragmentation function in Z decays
Experiment: OPAL (LEP2)
Inspire ID: 599181
Status: VALIDATED
Authors:
• Simone Amoroso
References:
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)

A study of b quark fragmentation function is presented using inclusively reconstructed weakly decaying B hadrons. The measurement uses about four million hadronic Z decays recorded in 1992-2000 with the OPAL detector at LEP.

Source code: OPAL_2003_I599181.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 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/UnstableFinalState.hh" #include "Rivet/Projections/Beam.hh" namespace Rivet { /// @brief OPAL b-fragmentation measurement for weak B-hadron decays /// @author Simone Amoroso class OPAL_2003_I599181 : public Analysis { public: /// Constructor DEFAULT_RIVET_ANALYSIS_CTOR(OPAL_2003_I599181); /// @name Analysis methods //@{ /// Book histograms and initialise projections before the run void init() { // Initialise and register projections declare(Beam(), "Beams"); declare(UnstableFinalState(), "UFS"); // Book histograms _histXbweak = bookHisto1D(1, 1, 1); _histMeanXbweak = bookProfile1D(2, 1, 1); } /// Perform the per-event analysis void analyze(const Event& event) { // Get event weight for histo filling const double weight = event.weight(); // 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); const UnstableFinalState& ufs = apply(event, "UFS"); // Get Bottom hadrons const Particles bhads = filter_select(ufs.particles(), isBottomHadron); for (const Particle& bhad : bhads) { // Check for weak decay, i.e. no more bottom present in children if (bhad.children(lastParticleWith(hasBottom)).empty()) { const double xp = bhad.E()/meanBeamMom; _histXbweak->fill(xp, weight); _histMeanXbweak->fill(_histMeanXbweak->bin(0).xMid(), xp, weight); } } } /// Normalise histograms etc., after the run void finalize() { normalize(_histXbweak); } //@} private: Histo1DPtr _histXbweak; Profile1DPtr _histMeanXbweak; }; // The hook for the plugin system DECLARE_RIVET_PLUGIN(OPAL_2003_I599181); }