Rivet analyses referenceATLAS_2020_I1790256Lund jet plane with charged particlesExperiment: ATLAS (LHC) Inspire ID: 1790256 Status: VALIDATED Authors:
Beam energies: (6500.0, 6500.0) GeV Run details:
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// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FastJets.hh"
4#include "Rivet/Projections/VetoedFinalState.hh"
5#include "Rivet/Projections/ChargedFinalState.hh"
6
7#include "fastjet/JetDefinition.hh"
8#include "fastjet/ClusterSequence.hh"
9#include "fastjet/contrib/LundGenerator.hh"
10
11namespace Rivet {
12
13 /// @brief Lund jet plane with charged particles
14 class ATLAS_2020_I1790256: public Analysis {
15 public:
16
17 RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2020_I1790256);
18
19 /// @name Analysis methods
20 //@{
21
22 void init() {
23
24 //Projections
25 FinalState fs(Cuts::abseta < 4.5);
26 FastJets jet4(fs, FastJets::ANTIKT, 0.4, JetAlg::Muons::NONE, JetAlg::Invisibles::NONE);
27 declare(jet4, "Jets");
28
29 ChargedFinalState tracks(Cuts::pT > 0.5*GeV && Cuts::abseta < 2.5);
30 declare(tracks, "tracks");
31
32 book(_h_lundplane, 1,1,1);
33
34 _h_vs.resize(13);
35 for (size_t i = 0; i < _h_vs.size(); ++i) {
36 book(_h_vs[i] , i+3 , 1, 1);
37 }
38
39 _h_hs.resize(19);
40 for (size_t i = 0; i < _h_hs.size(); ++i) {
41 book(_h_hs[i], i+16, 1, 1);
42 }
43
44
45 book(_njets, "_njets");
46
47 }
48
49 void analyze(const Event& event) {
50
51 const Jets jets = apply<JetAlg>(event, "Jets").jetsByPt(Cuts::pT > 300*GeV && Cuts::abseta < 2.1);
52
53 if (jets.size() < 2) vetoEvent;
54 if (jets[0].pT() < 675*GeV) vetoEvent;
55
56 if ( (jets[0].pT()/jets[1].pT()) > 1.5 ) vetoEvent;
57
58 _njets->fill(2);
59
60 const Particles& tracks = apply<ChargedFinalState>(event, "tracks").particlesByPt();
61
62 Particles intracks1;
63 Particles intracks2;
64
65 const Jet& j1 = jets[0];
66 const Jet& j2 = jets[1];
67
68
69 for (const Particle& p : tracks) {
70 const double dr = deltaR(j1, p, PSEUDORAPIDITY);
71 if (dr > 0.4) continue;
72 if (abs(p.pid()) == 13) continue;
73 intracks1.push_back(p);
74 }
75
76 for (const Particle& p : tracks) {
77 const double dr = deltaR(j2, p, PSEUDORAPIDITY);
78 if (dr > 0.4) continue;
79 if (abs(p.pid()) == 13) continue;
80 intracks2.push_back(p);
81 }
82
83 JetDefinition tjet1_def(fastjet::cambridge_algorithm, 10);
84 ClusterSequence tjet1_cs(intracks1, tjet1_def);
85 vector<PseudoJet> tjets1 = fastjet::sorted_by_pt(tjet1_cs.inclusive_jets(0.0));
86
87 JetDefinition tjet2_def(fastjet::cambridge_algorithm, 10);
88 ClusterSequence tjet2_cs(intracks2, tjet2_def);
89 vector<PseudoJet> tjets2 = fastjet::sorted_by_pt(tjet2_cs.inclusive_jets(0.0));
90
91 if (tjets1.size() < 1 || tjets2.size() < 1) vetoEvent;
92
93 fjcontrib::LundGenerator lund;
94 vector<fjcontrib::LundDeclustering> declusts1 = lund(tjets1[0]);
95 for (size_t idecl = 0; idecl < declusts1.size(); ++idecl) {
96 pair<double,double> coords = declusts1[idecl].lund_coordinates();
97 double X = -0.9163 + coords.first;
98 double Y = - log(declusts1[idecl].z());
99
100 if (X > 0 && X < 4.33 && Y > log(1/0.5) && Y < 8.6*log(1/0.5) ){
101
102 _h_lundplane->fill(X, Y);
103
104 double hdiv = (double)4.33/(double)13;
105 size_t i = floor(X/hdiv);
106 _h_vs[i]->fill(Y);
107
108 double vdiv = (8.6*log(1/0.5) - log(1/0.5))/(double)19;
109 size_t j = floor((Y - log(1/0.5))/vdiv);
110 _h_hs[j]->fill(X);
111
112 }
113 }
114
115 vector<fjcontrib::LundDeclustering> declusts2 = lund(tjets2[0]);
116 for (size_t idecl = 0; idecl < declusts2.size(); ++idecl) {
117 pair<double,double> coords = declusts2[idecl].lund_coordinates();
118
119 double X = -0.9163 + coords.first;
120 double Y = - log(declusts2[idecl].z());
121
122 if (X > 0 && X < 4.33 && Y > log(1/0.5) && Y < 8.6*log(1/0.5) ) {
123
124 _h_lundplane->fill(X, Y);
125
126 double hdiv = (double)4.33/(double)13;
127 size_t i = floor(X/hdiv);
128 _h_vs[i]->fill(Y);
129
130 double vdiv = (8.6*log(1/0.5) - log(1/0.5))/(double)19;
131 size_t j = floor((Y - log(1/0.5))/vdiv);
132 _h_hs[j]->fill(X);
133 }
134 }
135 }
136
137
138 void finalize() {
139
140 double area = _njets->sumW();
141 if (area > 0) {
142 scale(_h_lundplane, 1/area);
143 scale(_h_vs, 1/(area*0.333));
144 scale(_h_hs, 1/(area*0.277));
145 }
146
147 }
148
149 private:
150
151
152 Histo2DPtr _h_lundplane;
153 vector<Histo1DPtr> _h_vs, _h_hs;
154 CounterPtr _njets;
155 };
156
157
158 // The hook for the plugin system
159 RIVET_DECLARE_PLUGIN(ATLAS_2020_I1790256);
160}
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