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## Rivet analyses reference

### ATLAS_2020_I1790256

Lund jet plane with charged particles
Experiment: ATLAS (LHC)
Inspire ID: 1790256
Status: VALIDATED
Authors:
• Deepak Kar
References:
Beams: p+ p+
Beam energies: (6500.0, 6500.0) GeV
Run details:
• pp -> dijet production at 13 TeV, pTHatMin cut of 200 GeV suggested.

The prevalence of hadronic jets at the LHC requires that a deep understanding of jet formation and structure is achieved in order to reach the highest levels of experimental and theoretical precision. There have been many measurements of jet substructure at the LHC and previous colliders, but the targeted observables mix physical effects from various origins. Based on a recent proposal to factorize physical effects, this Letter presents a double-differential cross-section measurement of the Lund jet plane using 139 fb$^{-1}$ of $\sqrt{s}=13$ TeV proton-proton collision data collected with the ATLAS detector using jets with transverse momentum above 675 GeV. The measurement uses charged particles to achieve a fine angular resolution and is corrected for acceptance and detector effects. Several parton shower Monte Carlo models are compared with the data. No single model is found to be in agreement with the measured data across the entire plane.

Source code: ATLAS_2020_I1790256.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 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/FastJets.hh" #include "Rivet/Projections/VetoedFinalState.hh" #include "Rivet/Projections/ChargedFinalState.hh" #include "fastjet/JetDefinition.hh" #include "fastjet/ClusterSequence.hh" #include "fastjet/contrib/LundGenerator.hh" namespace Rivet { /// @brief Lund jet plane with charged particles class ATLAS_2020_I1790256: public Analysis { public: DEFAULT_RIVET_ANALYSIS_CTOR(ATLAS_2020_I1790256); /// @name Analysis methods //@{ void init() { //Projections FinalState fs(Cuts::abseta < 4.5); FastJets jet4(fs, FastJets::ANTIKT, 0.4, JetAlg::Muons::NONE, JetAlg::Invisibles::NONE); declare(jet4, "Jets"); ChargedFinalState tracks(Cuts::pT > 0.5*GeV && Cuts::abseta < 2.5); declare(tracks, "tracks"); book(_h_lundplane, 1,1,1); _h_vs.resize(13); for (size_t i = 0; i < _h_vs.size(); ++i) { book(_h_vs[i] , i+3 , 1, 1); } _h_hs.resize(19); for (size_t i = 0; i < _h_hs.size(); ++i) { book(_h_hs[i], i+16, 1, 1); } book(_njets, "_njets"); } void analyze(const Event& event) { const Jets jets = apply(event, "Jets").jetsByPt(Cuts::pT > 300*GeV && Cuts::abseta < 2.1); if (jets.size() < 2) vetoEvent; if (jets[0].pT() < 675*GeV) vetoEvent; if ( (jets[0].pT()/jets[1].pT()) > 1.5 ) vetoEvent; _njets->fill(2); const Particles& tracks = apply(event, "tracks").particlesByPt(); Particles intracks1; Particles intracks2; const Jet& j1 = jets[0]; const Jet& j2 = jets[1]; for (const Particle& p : tracks) { const double dr = deltaR(j1, p, PSEUDORAPIDITY); if (dr > 0.4) continue; if (abs(p.pid()) == 13) continue; intracks1.push_back(p); } for (const Particle& p : tracks) { const double dr = deltaR(j2, p, PSEUDORAPIDITY); if (dr > 0.4) continue; if (abs(p.pid()) == 13) continue; intracks2.push_back(p); } JetDefinition tjet1_def(fastjet::cambridge_algorithm, 10); ClusterSequence tjet1_cs(intracks1, tjet1_def); vector tjets1 = fastjet::sorted_by_pt(tjet1_cs.inclusive_jets(0.0)); JetDefinition tjet2_def(fastjet::cambridge_algorithm, 10); ClusterSequence tjet2_cs(intracks2, tjet2_def); vector tjets2 = fastjet::sorted_by_pt(tjet2_cs.inclusive_jets(0.0)); if (tjets1.size() < 1 || tjets2.size() < 1) vetoEvent; fjcontrib::LundGenerator lund; vector declusts1 = lund(tjets1[0]); for (size_t idecl = 0; idecl < declusts1.size(); ++idecl) { pair coords = declusts1[idecl].lund_coordinates(); double X = -0.9163 + coords.first; double Y = - log(declusts1[idecl].z()); if (X > 0 && X < 4.33 && Y > log(1/0.5) && Y < 8.6*log(1/0.5) ){ _h_lundplane->fill(X, Y); double hdiv = (double)4.33/(double)13; size_t i = floor(X/hdiv); _h_vs[i]->fill(Y); double vdiv = (8.6*log(1/0.5) - log(1/0.5))/(double)19; size_t j = floor((Y - log(1/0.5))/vdiv); _h_hs[j]->fill(X); } } vector declusts2 = lund(tjets2[0]); for (size_t idecl = 0; idecl < declusts2.size(); ++idecl) { pair coords = declusts2[idecl].lund_coordinates(); double X = -0.9163 + coords.first; double Y = - log(declusts2[idecl].z()); if (X > 0 && X < 4.33 && Y > log(1/0.5) && Y < 8.6*log(1/0.5) ) { _h_lundplane->fill(X, Y); double hdiv = (double)4.33/(double)13; size_t i = floor(X/hdiv); _h_vs[i]->fill(Y); double vdiv = (8.6*log(1/0.5) - log(1/0.5))/(double)19; size_t j = floor((Y - log(1/0.5))/vdiv); _h_hs[j]->fill(X); } } } void finalize() { double area = _njets->sumW(); scale(_h_lundplane, 1/area); scale(_h_vs, 1/(area*0.333)); scale(_h_hs, 1/(area*0.277)); } private: Histo2DPtr _h_lundplane; vector _h_vs, _h_hs; CounterPtr _njets; }; // The hook for the plugin system DECLARE_RIVET_PLUGIN(ATLAS_2020_I1790256); }