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## Rivet analyses reference

### D0_2009_S8349509

Z+jets angular distributions
Experiment: D0 (Tevatron Run 2)
Inspire ID: 826756
Status: VALIDATED
Authors:
• Frank Siegert
References:
Beams: p- p+
Beam energies: (980.0, 980.0) GeV
Run details:
• $p \bar{p} \to \mu^+ \mu^-$ + jets at 1960 GeV. Needs mass cut on lepton pair to avoid photon singularity, looser than $65 < m_{ee} < 115$ GeV.

First measurements at a hadron collider of differential cross sections for $Z (\to \mu\mu)$+jet+X production in $\Delta\phi(Z, j)$, $|\Delta y(Z, j)|$ and $|y_\mathrm{boost}(Z, j)|$. Vector boson production in association with jets is an excellent probe of QCD and constitutes the main background to many small cross section processes, such as associated Higgs production. These measurements are crucial tests of the predictions of perturbative QCD and current event generators, which have varied success in describing the data. Using these measurements as inputs in tuning event generators will increase the experimental sensitivity to rare signals.

Source code: D0_2009_S8349509.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 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/FinalState.hh" #include "Rivet/Projections/ZFinder.hh" #include "Rivet/Projections/FastJets.hh" namespace Rivet { /// @brief D0 Z+jets angular distributions class D0_2009_S8349509 : public Analysis { public: /// @name Constructors etc. //@{ /// Constructor D0_2009_S8349509() : Analysis("D0_2009_S8349509"), _inclusive_Z_sumofweights(0) { } //@} /// @name Analysis methods //@{ /// Book histograms void init() { Cut cut = Cuts::abseta < 1.7 && Cuts::pT > 15*GeV; ZFinder zfinder(FinalState(), cut, PID::MUON, 65*GeV, 115*GeV, 0.2, ZFinder::NOCLUSTER, ZFinder::TRACK); declare(zfinder, "ZFinder"); FastJets conefinder(zfinder.remainingFinalState(), FastJets::D0ILCONE, 0.5); declare(conefinder, "ConeFinder"); _h_dphi_jet_Z25 = bookHisto1D(1, 1, 1); _h_dphi_jet_Z45 = bookHisto1D(2, 1, 1); _h_dy_jet_Z25 = bookHisto1D(3, 1, 1); _h_dy_jet_Z45 = bookHisto1D(4, 1, 1); _h_yboost_jet_Z25 = bookHisto1D(5, 1, 1); _h_yboost_jet_Z45 = bookHisto1D(6, 1, 1); _h_dphi_jet_Z25_xs = bookHisto1D(1, 1, 2); _h_dphi_jet_Z45_xs = bookHisto1D(2, 1, 2); _h_dy_jet_Z25_xs = bookHisto1D(3, 1, 2); _h_dy_jet_Z45_xs = bookHisto1D(4, 1, 2); _h_yboost_jet_Z25_xs = bookHisto1D(5, 1, 2); _h_yboost_jet_Z45_xs = bookHisto1D(6, 1, 2); _inclusive_Z_sumofweights = 0; } void analyze(const Event& event) { const double weight = event.weight(); const ZFinder& zfinder = apply(event, "ZFinder"); if (zfinder.bosons().size() == 1) { // count inclusive sum of weights for histogram normalisation _inclusive_Z_sumofweights += weight; const FourMomentum& zmom = zfinder.bosons()[0].momentum(); if (zmom.pT() < 25*GeV) vetoEvent; Jets jets; foreach (const Jet& j, apply(event, "ConeFinder").jetsByPt(20*GeV)) { if (j.abseta() < 2.8) { jets.push_back(j); break; } } // Return if there are no jets: if (jets.size() < 1) { MSG_DEBUG("Skipping event " << numEvents() << " because no jets pass cuts "); vetoEvent; } const FourMomentum& jetmom = jets[0].momentum(); const double yZ = zmom.rapidity(); const double yjet = jetmom.rapidity(); const double dphi = deltaPhi(zmom, jetmom); const double dy = deltaRap(zmom, jetmom); const double yboost = fabs(yZ+yjet)/2; if (zmom.pT() > 25*GeV) { _h_dphi_jet_Z25->fill(dphi, weight); _h_dy_jet_Z25->fill(dy, weight); _h_yboost_jet_Z25->fill(yboost, weight); _h_dphi_jet_Z25_xs->fill(dphi, weight); _h_dy_jet_Z25_xs->fill(dy, weight); _h_yboost_jet_Z25_xs->fill(yboost, weight); } if (zmom.pT() > 45*GeV) { _h_dphi_jet_Z45->fill(dphi, weight); _h_dy_jet_Z45->fill(dy, weight); _h_yboost_jet_Z45->fill(yboost, weight); _h_dphi_jet_Z45_xs->fill(dphi, weight); _h_dy_jet_Z45_xs->fill(dy, weight); _h_yboost_jet_Z45_xs->fill(yboost, weight); } } } void finalize() { if (_inclusive_Z_sumofweights == 0) return; scale(_h_dphi_jet_Z25, 1/_inclusive_Z_sumofweights); scale(_h_dphi_jet_Z45, 1/_inclusive_Z_sumofweights); scale(_h_dy_jet_Z25, 1/_inclusive_Z_sumofweights); scale(_h_dy_jet_Z45, 1/_inclusive_Z_sumofweights); scale(_h_yboost_jet_Z25, 1/_inclusive_Z_sumofweights); scale(_h_yboost_jet_Z45, 1/_inclusive_Z_sumofweights); scale(_h_dphi_jet_Z25_xs, crossSectionPerEvent()); scale(_h_dphi_jet_Z45_xs, crossSectionPerEvent()); scale(_h_dy_jet_Z25_xs, crossSectionPerEvent()); scale(_h_dy_jet_Z45_xs, crossSectionPerEvent()); scale(_h_yboost_jet_Z25_xs, crossSectionPerEvent()); scale(_h_yboost_jet_Z45_xs, crossSectionPerEvent()); } //@} private: // Data members like post-cuts event weight counters go here private: /// @name Histograms (normalised) //@{ Histo1DPtr _h_dphi_jet_Z25; Histo1DPtr _h_dphi_jet_Z45; Histo1DPtr _h_dy_jet_Z25; Histo1DPtr _h_dy_jet_Z45; Histo1DPtr _h_yboost_jet_Z25; Histo1DPtr _h_yboost_jet_Z45; //@} /// @name Histograms (absolute cross sections) //@{ Histo1DPtr _h_dphi_jet_Z25_xs; Histo1DPtr _h_dphi_jet_Z45_xs; Histo1DPtr _h_dy_jet_Z25_xs; Histo1DPtr _h_dy_jet_Z45_xs; Histo1DPtr _h_yboost_jet_Z25_xs; Histo1DPtr _h_yboost_jet_Z45_xs; //@} double _inclusive_Z_sumofweights; }; // The hook for the plugin system DECLARE_RIVET_PLUGIN(D0_2009_S8349509); }