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## Rivet analyses reference

### EHS_1988_I265504

Charged-particle production in $K^+ p$, $\pi^+ p$ and $pp$ interactions at $250 \text{GeV}/c$
Experiment: EHS (SPS)
Inspire ID: 265504
Status: VALIDATED
Authors:
• Felix Riehn
References:
• Z.Phys.C39 (1988), 311
Beams: p+ p+, 0 p+, 0 p+
Beam energies: (250.0, 0.0); (250.0, 0.0); (250.0, 0.0) GeV
Run details:
• Inelastic interactions in CM frame, excluding slow protons in the lab. frame with p < 1.2 GeV/$c$

Measurement of charged particle production spectra in longitudinal and transverse momentum as well as rapidity by the EHS/NA22 collaboration at the SPS. Experiment was done with a fixed hydrogen target and beams of $p$, $\pi^+$ and $K^+$ with $250\,\text{GeV}/c$. Measured spectra are for positively charged hadrons $C^+$ and negative charge pions $\pi^-$. $C^+$ excludes slow protons with $p < 1.2\,\text{GeV}/c$ in the laboratory. Final spectra are in center-of-mass variables: $x_\mathrm{F}$, $y$ and $p_\mathrm{T}$.

Source code: EHS_1988_I265504.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 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/Beam.hh" #include "Rivet/Projections/ChargedFinalState.hh" #include "Rivet/Event.hh" namespace Rivet { class EHS_1988_I265504 : public Analysis { public: /// Constructor DEFAULT_RIVET_ANALYSIS_CTOR(EHS_1988_I265504); /// @name Analysis methods //@{ /// Book histograms and initialise projections before the run void init() { declare(ChargedFinalState(), "CFS"); declare(Beam(),"Beam"); switch ( beamIds().first ) { case PID::PIPLUS: _h_cpos_xF = bookHisto1D(1, 1, 1); _h_cpos_eta = bookHisto1D(3, 1, 1); _h_cpos_pT2 = bookHisto1D(5, 1, 1); _h_cneg_xF = bookHisto1D(2, 1, 1); _h_cneg_eta = bookHisto1D(4, 1, 1); _h_cneg_pT2 = bookHisto1D(6, 1, 1); break; case PID::KPLUS: _h_cpos_xF = bookHisto1D(1, 1, 2); _h_cpos_eta = bookHisto1D(3, 1, 2); _h_cpos_pT2 = bookHisto1D(5, 1, 2); _h_cneg_xF = bookHisto1D(2, 1, 2); _h_cneg_eta = bookHisto1D(4, 1, 2); _h_cneg_pT2 = bookHisto1D(6, 1, 2); break; case PID::PROTON: _h_cpos_xF = bookHisto1D(1, 1, 3); _h_cpos_eta = bookHisto1D(3, 1, 3); _h_cpos_pT2 = bookHisto1D(5, 1, 3); _h_cneg_xF = bookHisto1D(2, 1, 3); _h_cneg_eta = bookHisto1D(4, 1, 3); _h_cneg_pT2 = bookHisto1D(6, 1, 3); break; } // Calculate boost from lab to CM frame _beamboost = cmsTransform( beams() ); MSG_DEBUG("Boost vector: " << _beamboost ); // Transform beam into CMS frame Particle _beam_cm = beams().first; _beam_cm.transformBy(_beamboost); // Beam momentum in CM frame defines Feynman-x _pz_max = _beam_cm.pz(); } /// Perform the per-event analysis void analyze(const Event& event) { const double weight = event.weight(); const FinalState& fs = apply(event, "CFS"); for (const Particle& p: fs.particles()) { // Only interested in pi- or positively charged if (p.charge() < 0 && p.pid() != PID::PIMINUS) continue; // Slow proton cut: reject lab momenta < 1.2GeV if (p.pid() == PID::PROTON && p.p() < 1.2*GeV) continue; // Transform to cm frame const FourMomentum pcm = _beamboost.transform(p); const double xF = pcm.pz()/_pz_max; if (p.charge() > 0) { _h_cpos_xF->fill( xF, weight); _h_cpos_pT2->fill( p.pT2(), weight); _h_cpos_eta->fill( p.eta(), weight); } else if (p.pid() == PID::PIMINUS) { _h_cneg_xF->fill( xF, weight); _h_cneg_pT2->fill( p.pT2(), weight); _h_cneg_eta->fill( p.eta(), weight); } } } /// Normalise histograms etc., after the run void finalize() { scale( {_h_cpos_xF, _h_cpos_pT2,_h_cpos_eta, _h_cneg_xF, _h_cneg_eta, _h_cneg_pT2}, crossSection()/millibarn/sumOfWeights() ); } //@} /// @name Histograms //@{ LorentzTransform _beamboost; double _pz_max; Histo1DPtr _h_cpos_xF, _h_cpos_eta, _h_cpos_pT2; Histo1DPtr _h_cneg_xF, _h_cneg_eta, _h_cneg_pT2; //@} }; // The hook for the plugin system DECLARE_RIVET_PLUGIN(EHS_1988_I265504); }