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## Rivet analyses reference

### UA5_1982_S875503

UA5 multiplicity and pseudorapidity distributions for $pp$ and $p\bar{p}$.
Experiment: UA5 (SPS)
Inspire ID: 176647
Status: VALIDATED
Authors:
• Andy Buckley
• Christophe Vaillant
References:
• Phys.Lett.112B:183,1982
Beams: p- p+, p+ p+
Beam energies: (26.5, 26.5) GeV
Run details:
• Min bias QCD events at $\sqrt{s} = 53$\;GeV. Run with both $pp$ and $p\bar{p}$ beams.

Comparisons of multiplicity and pseudorapidity distributions for $pp$ and $p\bar{p}$ collisions at 53 GeV, based on the UA5 53 GeV runs in 1982. Data confirms the lack of significant difference between the two beams.

Source code: UA5_1982_S875503.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 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/ChargedFinalState.hh" #include "Rivet/Projections/TriggerUA5.hh" namespace Rivet { /// @brief UA5 multiplicity and \f$\eta \f$ distributions class UA5_1982_S875503 : public Analysis { public: /// Default constructor UA5_1982_S875503() : Analysis("UA5_1982_S875503") { _sumWTrig = 0; } /// @name Analysis methods //@{ /// Set up projections and book histos void init() { declare(TriggerUA5(), "Trigger"); declare(ChargedFinalState(-3.5, 3.5), "CFS"); // Book histos based on pp or ppbar beams if (beamIds().first == beamIds().second) { _hist_nch = bookHisto1D(2,1,1); _hist_eta = bookHisto1D(3,1,1); } else { _hist_nch = bookHisto1D(2,1,2); _hist_eta = bookHisto1D(4,1,1); } } void analyze(const Event& event) { // Trigger const TriggerUA5& trigger = apply(event, "Trigger"); if (!trigger.nsdDecision()) vetoEvent; const double weight = event.weight(); _sumWTrig += weight; // Get tracks const ChargedFinalState& cfs = apply(event, "CFS"); // Fill mean charged multiplicity histos _hist_nch->fill(_hist_nch->bin(0).xMid(), cfs.size()*weight); // Iterate over all tracks and fill eta histograms foreach (const Particle& p, cfs.particles()) { const double eta = p.abseta(); _hist_eta->fill(eta, weight); } } void finalize() { /// @todo Why the factor of 2 on Nch for ppbar? if (beamIds().first == beamIds().second) { scale(_hist_nch, 1.0/_sumWTrig); } else { scale(_hist_nch, 0.5/_sumWTrig); } scale(_hist_eta, 0.5/_sumWTrig); } //@} private: /// @name Counters //@{ double _sumWTrig; //@} /// @name Histogram collections //@{ Histo1DPtr _hist_nch; Histo1DPtr _hist_eta; //@} }; // The hook for the plugin system DECLARE_RIVET_PLUGIN(UA5_1982_S875503); }