Rivet analyses referenceATLAS_2018_I1635273W + jets production at 8 TeVExperiment: ATLAS (LHC) Inspire ID: 1635273 Status: VALIDATED Authors:
Beam energies: (4000.0, 4000.0) GeV Run details:
This paper presents a measurement of the W boson production cross section and the W+/W− cross-section ratio, both in association with jets, in proton-proton collisions at √s=8 TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is performed in final states containing one electron and missing transverse momentum using data corresponding to an integrated luminosity of 20.2 fb−1. Differential cross sections for events with at least one or two jets are presented for a range of observables, including jet transverse momenta and rapidities, the scalar sum of transverse momenta of the visible particles and the missing transverse momentum in the event, and the transverse momentum of the W boson. For a subset of the observables, the differential cross sections of positively and negatively charged W bosons are measured separately. In the cross-section ratio of W+/W− the dominant systematic uncertainties cancel out, improving the measurement precision by up to a factor of nine. The observables and ratios selected for this paper provide valuable input for the up quark, down quark, and gluon parton distribution functions of the proton. Source code: ATLAS_2018_I1635273.cc 1#include "Rivet/Analysis.hh"
2#include "Rivet/Projections/FinalState.hh"
3#include "Rivet/Projections/InvisibleFinalState.hh"
4#include "Rivet/Projections/FastJets.hh"
5#include "Rivet/Projections/PromptFinalState.hh"
6#include "Rivet/Projections/LeptonFinder.hh"
7
8namespace Rivet {
9
10
11 /// @brief W + jets production at 8 TeV
12 class ATLAS_2018_I1635273 : public Analysis {
13 public:
14
15 /// Constructor
16 RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2018_I1635273);
17
18
19 // Book histograms and initialise projections before the run
20 void init() {
21
22 // Get options from the new option system
23 // Default uses electrons
24 // EL looks for W->ev candidate
25 // MU looks for W->mv candidate
26 _mode = 0;
27 if ( getOption("LMODE") == "EL" ) _mode = 0;
28 if ( getOption("LMODE") == "MU" ) _mode = 1;
29
30 FinalState fs;
31 Cut cuts = Cuts::pT > 25*GeV && Cuts::abseta < 2.5;
32
33 // Get photons to dress leptons
34 // (Paper says "radiated photons", but there was
35 // no promptness requirement in the analysis code)
36 FinalState photons(Cuts::abspid == PID::PHOTON);
37
38 // Get dressed leptons
39 PromptFinalState leptons(Cuts::abspid == (_mode? PID::MUON : PID::ELECTRON), TauDecaysAs::NONPROMPT);
40 LeptonFinder dressedleptons(leptons, photons, 0.1, cuts);
41 declare(dressedleptons, "LeptonFinder");
42
43 // Get neutrinos for MET calculation
44 declare(InvisibleFinalState(OnlyPrompt::YES), "InvFS");
45
46 // jets
47 FastJets jets(fs, JetAlg::ANTIKT, 0.4, JetMuons::NONE);
48 declare(jets, "Jets");
49
50 // book histograms
51 book(_d["N_incl_pb"], 1, 1, 1);
52 book(_h["HT_1j_fb"], 6, 1, 1);
53 book(_h["W_pt_1j_fb"], 11, 1, 1);
54 book(_h["jet_pt1_1j_fb"], 16, 1, 1);
55 book(_h["jet_y1_1j_fb"], 21, 1, 1);
56 book(_h["jet_pt2_2j_fb"], 26, 1, 1);
57 book(_h["jet_y2_2j_fb"], 28, 1, 1);
58 book(_h["DeltaRj12_2j_fb"], 30, 1, 1);
59 book(_h["jet_mass12_2j_fb"], 32, 1, 1);
60 book(_d["N_pb"], 34, 1, 1);
61 book(_h["HT_2j_fb"], 36, 1, 1);
62 book(_h["W_pt_2j_fb"], 41, 1, 1);
63 book(_h["jet_pt1_2j_fb"], 46, 1, 1);
64 book(_h["el_eta_0j_pb"], 51, 1, 1);
65 book(_h["el_eta_1j_pb"], 56, 1, 1);
66
67 book(_d["Wplus_N_incl_pb"], 3, 1, 1);
68 book(_h["Wplus_HT_1j_fb"], 8, 1, 1);
69 book(_h["Wplus_W_pt_1j_fb"], 13, 1, 1);
70 book(_h["Wplus_jet_pt1_1j_fb"], 18, 1, 1);
71 book(_h["Wplus_jet_y1_1j_fb"], 23, 1, 1);
72 book(_h["Wplus_HT_2j_fb"], 38, 1, 1);
73 book(_h["Wplus_W_pt_2j_fb"], 43, 1, 1);
74 book(_h["Wplus_jet_pt1_2j_fb"], 48, 1, 1);
75 book(_h["Wplus_el_eta_0j_pb"], 53, 1, 1);
76 book(_h["Wplus_el_eta_1j_pb"], 58, 1, 1);
77
78 book(_d["Wminus_N_incl_pb"], 3, 1, 2);
79 book(_h["Wminus_HT_1j_fb"], 8, 1, 2);
80 book(_h["Wminus_W_pt_1j_fb"], 13, 1, 2);
81 book(_h["Wminus_jet_pt1_1j_fb"],18, 1, 2);
82 book(_h["Wminus_jet_y1_1j_fb"], 23, 1, 2);
83 book(_h["Wminus_HT_2j_fb"], 38, 1, 2);
84 book(_h["Wminus_W_pt_2j_fb"], 43, 1, 2);
85 book(_h["Wminus_jet_pt1_2j_fb"],48, 1, 2);
86 book(_h["Wminus_el_eta_0j_pb"], 53, 1, 2);
87 book(_h["Wminus_el_eta_1j_pb"], 58, 1, 2);
88
89 // and ratios
90 book(_r_disc, 3, 1, 3);
91 book(_r["WplusOverWminus_HT_1j_fb"], 8, 1, 3);
92 book(_r["WplusOverWminus_W_pt_1j_fb"], 13, 1, 3);
93 book(_r["WplusOverWminus_jet_pt1_1j_fb"], 18, 1, 3);
94 book(_r["WplusOverWminus_jet_y1_1j_fb"], 23, 1, 3);
95 book(_r["WplusOverWminus_HT_2j_fb"], 38, 1, 3);
96 book(_r["WplusOverWminus_W_pt_2j_fb"], 43, 1, 3);
97 book(_r["WplusOverWminus_jet_pt1_2j_fb"], 48, 1, 3);
98 book(_r["WplusOverWminus_el_eta_0j_pb"], 53, 1, 3);
99 book(_r["WplusOverWminus_el_eta_1j_pb"], 58, 1, 3);
100
101 }
102
103
104 // Perform the per-event analysis
105 void analyze(const Event& event) {
106
107 // retrieve the dressed electrons
108 const Particles& signal_leptons = apply<LeptonFinder>(event, "LeptonFinder").particlesByPt();
109 if (signal_leptons.size() != 1 ) vetoEvent;
110 const Particle& lepton = signal_leptons[0];
111
112 // calulate MET and mT
113 const Particles& invisibles = apply<InvisibleFinalState>(event, "InvFS").particles();
114 FourMomentum pMET = sum(invisibles, Kin::mom, FourMomentum()).setZ(0);
115 const double MET = pMET.pT() / GeV;
116 const double mT = sqrt( 2 * lepton.Et() / GeV * MET * (1 - cos(deltaPhi(lepton,pMET))));
117 if ( MET <= 25. ) vetoEvent;
118 if ( mT <= 40. ) vetoEvent;
119
120 // retrieve jets
121 Jets jets = apply<FastJets>(event, "Jets").jetsByPt(Cuts::pT > 30*GeV && Cuts::absrap < 4.4);
122
123 idiscardIfAnyDeltaRLess(jets, signal_leptons, 0.2);
124
125 // apply event selection on dR
126 for (const Jet& j : jets) {
127 if (deltaR(j, lepton) < 0.4) vetoEvent;
128 }
129
130 // calculate the observables
131 const double w_pt = (lepton.momentum() + pMET).pT() / GeV;
132 const size_t njets = jets.size();
133 double ST = sum(jets, Kin::pT, 0.0); // scalar pT sum of all selected jets
134 const double HT = ST + lepton.pT() / GeV + MET; //missET;
135
136 // fill W histograms
137 _d["N_pb"]->fill(njets);
138 for (size_t i = 0; i <= njets; ++i) {
139 _d["N_incl_pb"]->fill(i);
140 }
141 _h["el_eta_0j_pb"]->fill(lepton.abseta());
142
143 if (njets > 0) {
144 _h["HT_1j_fb"]->fill(HT);
145 _h["W_pt_1j_fb"]->fill(w_pt);
146 _h["jet_pt1_1j_fb"]->fill(jets[0].pT()/GeV);
147 _h["jet_y1_1j_fb"]->fill(jets[0].absrap());
148 _h["el_eta_1j_pb"]->fill(lepton.abseta());
149 }
150 if (njets > 1) {
151 _h["HT_2j_fb"]->fill(HT);
152 _h["W_pt_2j_fb"]->fill(w_pt);
153 _h["jet_pt1_2j_fb"]->fill(jets[0].pT()/GeV);
154 _h["DeltaRj12_2j_fb"]->fill(deltaR(jets[0],jets[1]));
155 _h["jet_pt2_2j_fb"]->fill(jets[1].pT()/GeV);
156 _h["jet_y2_2j_fb"]->fill(jets[1].absrap());
157 _h["jet_mass12_2j_fb"]->fill( (jets[0].mom()+jets[1].mom()).mass()/GeV);
158 }
159 // fill W+ histograms
160 if (lepton.charge() > 0) {
161 for (size_t i = 0; i <= njets; ++i) {
162 _d["Wplus_N_incl_pb"]->fill(i);
163 }
164 _h["Wplus_el_eta_0j_pb"]->fill(lepton.abseta());
165 if (njets > 0) {
166 _h["Wplus_HT_1j_fb"]->fill(HT);
167 _h["Wplus_W_pt_1j_fb"]->fill(w_pt);
168 _h["Wplus_jet_pt1_1j_fb"]->fill(jets[0].pT()/GeV);
169 _h["Wplus_jet_y1_1j_fb"]->fill(jets[0].absrap());
170 _h["Wplus_el_eta_1j_pb"]->fill(lepton.abseta());
171 if (njets > 1) {
172 _h["Wplus_HT_2j_fb"]->fill(HT);
173 _h["Wplus_W_pt_2j_fb"]->fill(w_pt);
174 _h["Wplus_jet_pt1_2j_fb"]->fill(jets[0].pT()/GeV);
175 }
176 }
177 }
178 // fill W- histograms
179 if (lepton.charge() < 0) {
180 for (size_t i = 0; i <= njets; ++i) {
181 _d["Wminus_N_incl_pb"]->fill(i);
182 }
183 _h["Wminus_el_eta_0j_pb"]->fill(lepton.abseta());
184 if (njets > 0) {
185 _h["Wminus_HT_1j_fb"]->fill(HT);
186 _h["Wminus_W_pt_1j_fb"]->fill(w_pt);
187 _h["Wminus_jet_pt1_1j_fb"]->fill(jets[0].pT()/GeV);
188 _h["Wminus_jet_y1_1j_fb"]->fill(jets[0].absrap());
189 _h["Wminus_el_eta_1j_pb"]->fill(lepton.abseta());
190 if (njets > 1) {
191 _h["Wminus_HT_2j_fb"]->fill(HT);
192 _h["Wminus_W_pt_2j_fb"]->fill(w_pt);
193 _h["Wminus_jet_pt1_2j_fb"]->fill(jets[0].pT()/GeV);
194 }
195 }
196 }
197 }
198
199
200
201 void finalize() {
202 const double scalefactor_fb = crossSection() / sumOfWeights() / femtobarn;
203 const double scalefactor_pb = crossSection() / sumOfWeights() / picobarn;
204
205 scale(_d, scalefactor_pb);
206 for (auto& hit : _h){
207 if (hit.first.find("_fb") != string::npos) scale(hit.second, scalefactor_fb);
208 else scale(hit.second, scalefactor_pb);
209 }
210 for (auto& rit : _r) {
211 string ratio_label = "WplusOverWminus";
212 string num_name = rit.first;
213 string denom_name = rit.first;
214 num_name.replace(rit.first.find(ratio_label),ratio_label.length(),"Wplus");
215 denom_name.replace(rit.first.find(ratio_label),ratio_label.length(),"Wminus");
216 divide(_h[num_name], _h[denom_name], rit.second);
217 }
218 divide(_d["Wplus_N_incl_pb"], _d["Wminus_N_incl_pb"], _r_disc);
219 }
220
221 protected:
222 // Data members like post-cuts event weight counters go here
223 size_t _mode;
224
225 private:
226 map<string, BinnedHistoPtr<int>> _d;
227 map<string, Histo1DPtr> _h;
228 map<string, Estimate1DPtr> _r;
229 BinnedEstimatePtr<int> _r_disc;
230 };
231
232 RIVET_DECLARE_PLUGIN(ATLAS_2018_I1635273);
233}
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