rivet is hosted by Hepforge, IPPP Durham

## Rivet analyses reference

### CMS_2013_I1209721

Azimuthal correlations and event shapes in $Z$ + jets in $pp$ collisions at 7 TeV
Experiment: CMS (LHC)
Inspire ID: 1209721
Status: VALIDATED
Authors:
• Io Odderskov
References:
Measurements are presented of event shapes and azimuthal correlations in the inclusive production of a Z boson in association with jets in proton-proton collisions. The data correspond to an integrated luminosity of 5.0/fb, collected with the CMS detector at the CERN LHC at $\sqrt{s} = 7$\;TeV. This to test perturbative QCD predictions and evaluate a substantial background to most physics channels. Studies performed as a function of jet multiplicity for inclusive $Z$ boson production and for $Z$ bosons with transverse-momenta greater than 150\;GeV, are compared to predictions from Monte Carlo event generators that include leading-order multiparton matrix-element (with up to four hard partons in the final state) and next-to-leading-order simulations of Z + 1-jet events. The results are corrected for detector effects, and can therefore be used as input to improve models for describing these processes.
  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 #include "Rivet/Analysis.hh" #include "Rivet/Projections/FinalState.hh" #include "Rivet/Projections/FastJets.hh" #include "Rivet/Projections/ZFinder.hh" #include "Rivet/Projections/Thrust.hh" namespace Rivet { /// CMS Z+jets delta(phi) and jet thrust measurement at 7 TeV class CMS_2013_I1209721 : public Analysis { public: CMS_2013_I1209721() : Analysis("CMS_2013_I1209721") { } /// Book projections and histograms void init() { // Full final state const FinalState fs((Cuts::etaIn(-5.0,5.0))); declare(fs, "FS"); // Z finders for electrons and muons Cut cuts = Cuts::abseta < 2.4 && Cuts::pT > 20*GeV; const ZFinder zfe(fs, cuts, PID::ELECTRON, 71*GeV, 111*GeV); const ZFinder zfm(fs, cuts, PID::MUON, 71*GeV, 111*GeV); declare(zfe, "ZFE"); declare(zfm, "ZFM"); // Jets const FastJets jets(fs, FastJets::ANTIKT, 0.5); declare(jets, "JETS"); // Book histograms from data for (size_t i = 0; i < 2; ++i) { book(_histDeltaPhiZJ1_1[i] ,1+i*9, 1, 1); book(_histDeltaPhiZJ1_2[i] ,2+i*9, 1, 1); book(_histDeltaPhiZJ1_3[i] ,4+i*9, 1, 1); book(_histDeltaPhiZJ2_3[i] ,5+i*9, 1, 1); book(_histDeltaPhiZJ3_3[i] ,3+i*9, 1, 1); book(_histDeltaPhiJ1J2_3[i] ,6+i*9, 1, 1); book(_histDeltaPhiJ1J3_3[i] ,7+i*9, 1, 1); book(_histDeltaPhiJ2J3_3[i] ,8+i*9, 1, 1); book(_histTransvThrust[i] ,9+i*9, 1, 1); } } void analyze(const Event& event) { const double weight = 1.0; // Apply the Z finders const ZFinder& zfe = apply(event, "ZFE"); const ZFinder& zfm = apply(event, "ZFM"); // Choose the Z candidate (there must be one) if (zfe.empty() && zfm.empty()) vetoEvent; const Particles& z = !zfm.empty() ? zfm.bosons() : zfe.bosons(); const Particles& leptons = !zfm.empty() ? zfm.constituents() : zfe.constituents(); // Determine whether we are in the boosted regime const bool is_boosted = (z[0].pT() > 150*GeV); // Build the jets const FastJets& jetfs = apply(event, "JETS"); const Jets& jets = jetfs.jetsByPt(Cuts::pT > 50*GeV && Cuts::abseta < 2.5); // Clean the jets against the lepton candidates, as in the paper, with a deltaR cut of 0.4 against the clustered leptons vector cleanedJets; for (size_t i = 0; i < jets.size(); ++i) { bool isolated = true; for (size_t j = 0; j < 2; ++j) { if (deltaR(leptons[j], jets[i]) < 0.4) { isolated = false; break; } } if (isolated) cleanedJets.push_back(&jets[i]); } // Require at least 1 jet const unsigned int Njets = cleanedJets.size(); if (Njets < 1) vetoEvent; // Now compute the thrust // Collect Z and jets transverse momenta to calculate transverse thrust vector momenta; momenta.clear(); Vector3 mom = z[0].p3(); mom.setZ(0); momenta.push_back(mom); for (size_t i = 0; i < cleanedJets.size(); ++i) { Vector3 mj = cleanedJets[i]->momentum().p3(); mj.setZ(0); momenta.push_back(mj); } if (momenta.size() <= 2){ // We need to use a ghost so that Thrust.calc() doesn't return 1. momenta.push_back(Vector3(0.0000001,0.0000001,0.)); } Thrust thrust; thrust.calc(momenta); const double T = thrust.thrust(); FILLx2(_histTransvThrust, is_boosted, log(max(1-T, 1e-6)), weight); const double dphiZJ1 = deltaPhi(z[0], *cleanedJets[0]); FILLx2(_histDeltaPhiZJ1_1, is_boosted, dphiZJ1, weight); if (Njets > 1) { FILLx2(_histDeltaPhiZJ1_2, is_boosted, dphiZJ1, weight); if (Njets > 2) { FILLx2(_histDeltaPhiZJ1_3, is_boosted, dphiZJ1, weight); FILLx2(_histDeltaPhiZJ2_3, is_boosted, deltaPhi(z[0], *cleanedJets[1]), weight); FILLx2(_histDeltaPhiZJ3_3, is_boosted, deltaPhi(z[0], *cleanedJets[2]), weight); FILLx2(_histDeltaPhiJ1J2_3, is_boosted, deltaPhi(*cleanedJets[0], *cleanedJets[1]), weight); FILLx2(_histDeltaPhiJ1J3_3, is_boosted, deltaPhi(*cleanedJets[0], *cleanedJets[2]), weight); FILLx2(_histDeltaPhiJ2J3_3, is_boosted, deltaPhi(*cleanedJets[1], *cleanedJets[2]), weight); } } } /// Normalizations /// @note Most of these data normalizations neglect the overflow bins void finalize() { for (size_t i = 0; i < 2; ++i) { normalize(_histDeltaPhiZJ1_1[i], 1, false); normalize(_histDeltaPhiZJ1_2[i], 1, false); normalize(_histDeltaPhiZJ1_3[i], 1, false); normalize(_histDeltaPhiZJ2_3[i], 1, false); normalize(_histDeltaPhiZJ3_3[i], 1, false); normalize(_histDeltaPhiJ1J2_3[i], 1, false); normalize(_histDeltaPhiJ1J3_3[i], 1, false); normalize(_histDeltaPhiJ2J3_3[i], 1, false); normalize(_histTransvThrust[i]); } } private: // Define a helper to appropriately fill both unboosted and boosted histo versions void FILLx2(Histo1DPtr* HNAME, bool is_boosted, double VAL, double weight) { double x = VAL; for (size_t i = 0; i < 2; ++i) { if (i == 0 || is_boosted) HNAME[i]->fill(x, weight); } } // Arrays of unboosted/boosted histos Histo1DPtr _histDeltaPhiZJ1_1[2]; Histo1DPtr _histDeltaPhiZJ1_2[2]; Histo1DPtr _histDeltaPhiZJ1_3[2]; Histo1DPtr _histDeltaPhiZJ2_3[2]; Histo1DPtr _histDeltaPhiZJ3_3[2]; Histo1DPtr _histDeltaPhiJ1J2_3[2]; Histo1DPtr _histDeltaPhiJ1J3_3[2]; Histo1DPtr _histDeltaPhiJ2J3_3[2]; Histo1DPtr _histTransvThrust[2]; }; DECLARE_RIVET_PLUGIN(CMS_2013_I1209721); }