rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

STAR_2009_UE_HELEN

UE measurement in $pp$ at 200 GeV
Experiment: STAR (RHIC)
Spires ID: None
Status: PRELIMINARY
Authors:
• Helen Caines
• Hendrik Hoeth
References:
Beams: p+ p+
Beam energies: (100.0, 100.0) GeV
Run details:
• $pp$ at 200 GeV

WARNING! Mark as "STAR preliminary" and contact authors when using this! UE analysis similar to Rick Field's leading jet analysis. SIScone with radius/resolution parameter R=0.7 is used. Particles with $pT > 0.2 \text{GeV}$ and $|\eta| < 1$ are included in the analysis. All particles are assumed to have zero mass. Only jets with neutral energy $< 0.7$ are included. For the transMIN and transMAX $\Delta(\phi)$ is between $\pi/3$ and $2\pi/3$, and $\Delta(\eta) < 2.0$. For the jet region the area of the jet is used for the normalization, i.e. the scaling factor is $\pi R^2$ and not $\mathrm{d}\phi\mathrm{d}\eta$ (this is different from what Rick Field does!). The tracking efficiency is $\sim 0.8$, but that is an approximation, as below $pT \sim 0.6 \text{GeV}$ it is falling quite steeply.

Source code: STAR_2009_UE_HELEN.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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/ChargedFinalState.hh" #include "Rivet/Projections/NeutralFinalState.hh" #include "Rivet/Projections/MergedFinalState.hh" #include "Rivet/Projections/VetoedFinalState.hh" #include "Rivet/Projections/FastJets.hh" #include "fastjet/SISConePlugin.hh" namespace Rivet { /// @brief STAR underlying event /// @author Hendrik Hoeth class STAR_2009_UE_HELEN : public Analysis { public: /// Constructor STAR_2009_UE_HELEN() : Analysis("STAR_2009_UE_HELEN") { } /// @name Analysis methods //@{ void init() { // Charged final state, |eta|<1, pT>0.2GeV const ChargedFinalState cfs(-1.0, 1.0, 0.2*GeV); declare(cfs, "CFS"); // Neutral final state, |eta|<1, ET>0.2GeV (needed for the jets) const NeutralFinalState nfs(-1.0, 1.0, 0.2*GeV); declare(nfs, "NFS"); // STAR can't see neutrons and K^0_L VetoedFinalState vfs(nfs); vfs.vetoNeutrinos(); vfs.addVetoPairId(PID::K0L); vfs.addVetoPairId(PID::NEUTRON); declare(vfs, "VFS"); // Jets are reconstructed from charged and neutral particles, // and the cuts are different (pT vs. ET), so we need to merge them. const MergedFinalState jfs(cfs, vfs); declare(jfs, "JFS"); // SISCone, R = 0.7, overlap_threshold = 0.75 declare(FastJets(jfs, FastJets::SISCONE, 0.7), "AllJets"); // Book histograms _hist_pmaxnchg = bookProfile1D( 1, 1, 1); _hist_pminnchg = bookProfile1D( 2, 1, 1); _hist_anchg = bookProfile1D( 3, 1, 1); } // Do the analysis void analyze(const Event& e) { const FinalState& cfs = apply(e, "CFS"); if (cfs.particles().size() < 1) { MSG_DEBUG("Failed multiplicity cut"); vetoEvent; } const Jets& alljets = apply(e, "AllJets").jetsByPt(); MSG_DEBUG("Total jet multiplicity = " << alljets.size()); // The jet acceptance region is |eta|<(1-R)=0.3 (with R = jet radius) // Jets also must have a neutral energy fraction of < 0.7 Jets jets; foreach (const Jet jet, alljets) { if (jet.neutralEnergy()/jet.totalEnergy() < 0.7 && jet.abseta() < 0.3) jets.push_back(jet); } // This analysis requires a di-jet like event. // WARNING: There is more data in preparation, some of which // does _not_ have this constraint! if (jets.size() != 2) { MSG_DEBUG("Failed jet multiplicity cut"); vetoEvent; } // The di-jet constraints in this analysis are: // - 2 and only 2 jets in the acceptance region // - delta(Phi) between the jets is > 150 degrees // - Pt_awayjet/Pt_towards_jet > 0.7 if (deltaPhi(jets[0].phi(), jets[1].phi()) <= 5*PI/6 || jets[1].pT()/jets[0].pT() <= 0.7) { MSG_DEBUG("Failed di-jet criteria"); vetoEvent; } // Now lets start ... const double jetphi = jets[0].phi(); const double jetpT = jets[0].pT(); // Get the event weight const double weight = e.weight(); size_t numTrans1(0), numTrans2(0), numAway(0); // Calculate all the charged stuff foreach (const Particle& p, cfs.particles()) { const double dPhi = deltaPhi(p.phi(), jetphi); const double pT = p.pT(); const double phi = p.phi(); double rotatedphi = phi - jetphi; while (rotatedphi < 0) rotatedphi += 2*PI; // @TODO: WARNING: The following lines are a hack to correct // for the STAR tracking efficiency. Once we have the // final numbers (corrected to hadron level), we need // to remove this!!!! if (1.0*rand()/static_cast(RAND_MAX) > 0.87834-exp(-1.48994-0.788432*pT)) { continue; } // -------- end of efficiency hack ------- if (dPhi < PI/3.0) { // toward } else if (dPhi < 2*PI/3.0) { if (rotatedphi <= PI) { ++numTrans1; } else { ++numTrans2; } } else { ++numAway; } } // end charged particle loop // Fill the histograms _hist_pmaxnchg->fill(jetpT, (numTrans1>numTrans2 ? numTrans1 : numTrans2)/(2*PI/3), weight); _hist_pminnchg->fill(jetpT, (numTrans1fill(jetpT, numAway/(PI*0.7*0.7), weight); // jet area = pi*R^2 } void finalize() { // } //@} private: Profile1DPtr _hist_pmaxnchg; Profile1DPtr _hist_pminnchg; Profile1DPtr _hist_anchg; }; // The hook for the plugin system DECLARE_RIVET_PLUGIN(STAR_2009_UE_HELEN); }