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## Rivet analyses reference

### CDF_2010_S8591881_DY

CDF Run 2 underlying event in Drell-Yan
Experiment: CDF (Tevatron Run 2)
Inspire ID: 849042
Status: VALIDATED
Authors:
• Hendrik Hoeth
References:
• Phys.Rev.D82:034001,2010
Beams: p- p+
Beam energies: (980.0, 980.0) GeV
Run details:
• ppbar collisions at 1960 GeV. * Drell-Yan events with $Z/\gamma* -> e e$ and $Z/\gamma* -> \mu\mu$. * A mass cut $m_{ll} > 70 \text{GeV}$ can be applied on generator level. * Particles with $c \tau > 10 \text{mm}$ should be set stable.

Deepak Kar and Rick Field's measurement of the underlying event in Drell-Yan events. $Z -> ee$ and $Z -> \mu\mu$ events are selected using a $Z$ mass window cut between 70 and 110 GeV. Toward'', away'' and transverse'' regions are defined in the same way as in the original (2001) CDF underlying event analysis. The reconstructed $Z$ defines the $\phi$ direction of the toward region. The leptons are ignored after the $Z$ has been reconstructed. Thus the region most sensitive to the underlying event is the toward region (the recoil jet is boosted into the away region).

Source code: CDF_2010_S8591881_DY.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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/ChargedFinalState.hh" #include "Rivet/Projections/ChargedLeptons.hh" namespace Rivet { /// @brief CDF Run II underlying event in Drell-Yan /// @author Hendrik Hoeth /// /// Measurement of the underlying event in Drell-Yan /// \f$Z/\gamma^* \to e^+ e^- \f$ and /// \f$Z/\gamma^* \to \mu^+ \mu^- \f$ events. The reconstructed /// Z defines the \f$\phi \f$ orientation. A Z mass window cut is applied. /// /// @par Run conditions /// /// @arg \f$\sqrt{s} = \f$ 1960 GeV /// @arg produce Drell-Yan events /// @arg Set particles with c*tau > 10 mm stable /// @arg Z decay mode: Z -> e+e- and Z -> mu+mu- /// @arg gamma decay mode: gamma -> e+e- and gamma -> mu+mu- /// @arg minimum invariant mass of the fermion pair coming from the Z/gamma: 70 GeV class CDF_2010_S8591881_DY : public Analysis { public: /// Constructor CDF_2010_S8591881_DY() : Analysis("CDF_2010_S8591881_DY") { } /// @name Analysis methods //@{ void init() { // Set up projections const ChargedFinalState cfs(-1.0, 1.0, 0.5*GeV); const ChargedFinalState clfs(-1.0, 1.0, 20*GeV); declare(cfs, "FS"); declare(ChargedLeptons(clfs), "CL"); // Book histograms _hist_tnchg = bookProfile1D( 1, 1, 1); _hist_pnchg = bookProfile1D( 1, 1, 2); _hist_anchg = bookProfile1D( 1, 1, 3); _hist_pmaxnchg = bookProfile1D( 2, 1, 1); _hist_pminnchg = bookProfile1D( 2, 1, 2); _hist_pdifnchg = bookProfile1D( 2, 1, 3); _hist_tcptsum = bookProfile1D( 3, 1, 1); _hist_pcptsum = bookProfile1D( 3, 1, 2); _hist_acptsum = bookProfile1D( 3, 1, 3); _hist_pmaxcptsum = bookProfile1D( 4, 1, 1); _hist_pmincptsum = bookProfile1D( 4, 1, 2); _hist_pdifcptsum = bookProfile1D( 4, 1, 3); _hist_tcptave = bookProfile1D( 5, 1, 1); _hist_pcptave = bookProfile1D( 5, 1, 2); _hist_tcptmax = bookProfile1D( 6, 1, 1); _hist_pcptmax = bookProfile1D( 6, 1, 2); _hist_zptvsnchg = bookProfile1D( 7, 1, 1); _hist_cptavevsnchg = bookProfile1D( 8, 1, 1); _hist_cptavevsnchgsmallzpt = bookProfile1D( 9, 1, 1); } /// Do the analysis void analyze(const Event& e) { 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 < 1) { MSG_DEBUG("Failed multiplicity cut"); vetoEvent; } // Get the event weight const double weight = e.weight(); // Get the leptons const Particles& leptons = apply(e, "CL").chargedLeptons(); // We want exactly two leptons of the same flavour. MSG_DEBUG("lepton multiplicity = " << leptons.size()); if (leptons.size() != 2 || leptons[0].pid() != -leptons[1].pid() ) vetoEvent; // Lepton pT > 20 GeV if (leptons[0].pT()/GeV <= 20 || leptons[1].pT()/GeV <= 20) vetoEvent; // Lepton pair should have an invariant mass between 70 and 110 and |eta| < 6 const FourMomentum dilepton = leptons[0].momentum() + leptons[1].momentum(); if (!inRange(dilepton.mass()/GeV, 70., 110.) || fabs(dilepton.eta()) >= 6) vetoEvent; MSG_DEBUG("Dilepton mass = " << dilepton.mass()/GeV << " GeV"); MSG_DEBUG("Dilepton pT = " << dilepton.pT()/GeV << " GeV"); // Calculate the observables size_t numToward(0), numAway(0); long int numTrans1(0), numTrans2(0); double ptSumToward(0.0), ptSumTrans1(0.0), ptSumTrans2(0.0), ptSumAway(0.0); double ptMaxToward(0.0), ptMaxTrans1(0.0), ptMaxTrans2(0.0), ptMaxAway(0.0); const double phiZ = dilepton.azimuthalAngle(); const double pTZ = dilepton.pT(); /// @todo Replace with foreach for (Particles::const_iterator p = fs.particles().begin(); p != fs.particles().end(); ++p) { // Don't use the leptons /// @todo Replace with PID::isLepton if (abs(p->pid()) < 20) continue; const double dPhi = deltaPhi(p->momentum().phi(), phiZ); const double pT = p->pT(); double rotatedphi = p->momentum().phi() - phiZ; while (rotatedphi < 0) rotatedphi += 2*PI; if (dPhi < PI/3.0) { ptSumToward += pT; ++numToward; if (pT > ptMaxToward) ptMaxToward = pT; } else if (dPhi < 2*PI/3.0) { if (rotatedphi <= PI) { ptSumTrans1 += pT; ++numTrans1; if (pT > ptMaxTrans1) ptMaxTrans1 = pT; } else { ptSumTrans2 += pT; ++numTrans2; if (pT > ptMaxTrans2) ptMaxTrans2 = pT; } } else { ptSumAway += pT; ++numAway; if (pT > ptMaxAway) ptMaxAway = pT; } // We need to subtract the two leptons from the number of particles to get the correct multiplicity _hist_cptavevsnchg->fill(numParticles-2, pT, weight); if (pTZ < 10) _hist_cptavevsnchgsmallzpt->fill(numParticles-2, pT, weight); } // Fill the histograms _hist_tnchg->fill(pTZ, numToward/(4*PI/3), weight); _hist_pnchg->fill(pTZ, (numTrans1+numTrans2)/(4*PI/3), weight); _hist_pmaxnchg->fill(pTZ, (numTrans1>numTrans2 ? numTrans1 : numTrans2)/(2*PI/3), weight); _hist_pminnchg->fill(pTZ, (numTrans1fill(pTZ, abs(numTrans1-numTrans2)/(2*PI/3), weight); _hist_anchg->fill(pTZ, numAway/(4*PI/3), weight); _hist_tcptsum->fill(pTZ, ptSumToward/(4*PI/3), weight); _hist_pcptsum->fill(pTZ, (ptSumTrans1+ptSumTrans2)/(4*PI/3), weight); _hist_pmaxcptsum->fill(pTZ, (ptSumTrans1>ptSumTrans2 ? ptSumTrans1 : ptSumTrans2)/(2*PI/3), weight); _hist_pmincptsum->fill(pTZ, (ptSumTrans1fill(pTZ, fabs(ptSumTrans1-ptSumTrans2)/(2*PI/3), weight); _hist_acptsum->fill(pTZ, ptSumAway/(4*PI/3), weight); if (numToward > 0) { _hist_tcptave->fill(pTZ, ptSumToward/numToward, weight); _hist_tcptmax->fill(pTZ, ptMaxToward, weight); } if ((numTrans1+numTrans2) > 0) { _hist_pcptave->fill(pTZ, (ptSumTrans1+ptSumTrans2)/(numTrans1+numTrans2), weight); _hist_pcptmax->fill(pTZ, (ptMaxTrans1 > ptMaxTrans2 ? ptMaxTrans1 : ptMaxTrans2), weight); } // We need to subtract the two leptons from the number of particles to get the correct multiplicity _hist_zptvsnchg->fill(numParticles-2, pTZ, weight); } void finalize() { } //@} private: Profile1DPtr _hist_tnchg; Profile1DPtr _hist_pnchg; Profile1DPtr _hist_pmaxnchg; Profile1DPtr _hist_pminnchg; Profile1DPtr _hist_pdifnchg; Profile1DPtr _hist_anchg; Profile1DPtr _hist_tcptsum; Profile1DPtr _hist_pcptsum; Profile1DPtr _hist_pmaxcptsum; Profile1DPtr _hist_pmincptsum; Profile1DPtr _hist_pdifcptsum; Profile1DPtr _hist_acptsum; Profile1DPtr _hist_tcptave; Profile1DPtr _hist_pcptave; Profile1DPtr _hist_tcptmax; Profile1DPtr _hist_pcptmax; Profile1DPtr _hist_zptvsnchg; Profile1DPtr _hist_cptavevsnchg; Profile1DPtr _hist_cptavevsnchgsmallzpt; }; // The hook for the plugin system DECLARE_RIVET_PLUGIN(CDF_2010_S8591881_DY); }