Rivet analyses referenceATLAS_2016_I1469071Measurement of the $WZ$ production cross section at 13 TeVExperiment: ATLAS (LHC) Inspire ID: 1469071 Status: VALIDATED Authors:
Beam energies: (6500.0, 6500.0) GeV Run details:
The production of $W^\pm Z$ events in proton--proton collisions at a centre-of-mass energy of 13 TeV is measured with the ATLAS detector at the LHC. The collected data correspond to an integrated luminosity of 3.2 fb${}^{-1}$ . The $W^\pm Z$ candidates are reconstructed using leptonic decays of the gauge bosons into electrons or muons. The measured inclusive cross section in the detector fiducial region for leptonic decay modes is $\sigma(W^\pm Z\to\ell^\prime\nu\ell\ell \text{fid.}) = 63.2\pm 3.2$(stat.)$\pm 2.6$(sys.)$\pm 1.5$(lumi.) fb. In comparison, the next-to-leading-order Standard Model prediction is 53.4-2.8+3.6 fb. The extrapolation of the measurement from the fiducial to the total phase space yields $\sigma(W^\pm Z\text{tot.})=50.6\pm 2.6$(stat.)$\pm 2.0$(sys.)$\pm 0.9$(th.)$\pm 1.2$(lumi.) pb, in agreement with a recent next-to-next-to-leading-order calculation of 48.2-1.0+1.1 pb. The cross section as a function of jet multiplicity is also measured, together with the charge-dependent $W^+Z$ and $W^-Z$ cross sections and their ratio. Uses SM neutrino-lepton flavour matching and a resonant shape algorithm assuming the Standard Model, to match the MC-based correction to the fiducial region applied in the paper. This routine is therefore only valid under the assumption of the Standard Model and cannot be used for BSM reinterpretation. Source code: ATLAS_2016_I1469071.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4#include "Rivet/Projections/FastJets.hh"
5#include "Rivet/Projections/IdentifiedFinalState.hh"
6#include "Rivet/Projections/PromptFinalState.hh"
7#include "Rivet/Projections/LeptonFinder.hh"
8#include "Rivet/Projections/VetoedFinalState.hh"
9
10namespace Rivet {
11
12
13 /// @brief Measurement of the WZ production cross section at 13 TeV
14 class ATLAS_2016_I1469071 : public Analysis {
15 public:
16
17 /// Constructor
18 RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2016_I1469071);
19
20 /// @name Analysis methods
21 /// @{
22
23 /// Book histograms and initialise projections before the run
24 void init() {
25
26 // Lepton cuts
27 Cut FS_Zlept = Cuts::abseta < 2.5 && Cuts::pT > 15*GeV;
28
29 FinalState fs;
30 Cut fs_z = Cuts::abseta < 2.5 && Cuts::pT > 15*GeV;
31 Cut fs_j = Cuts::abseta < 4.5 && Cuts::pT > 25*GeV;
32
33 // Get photons to dress leptons
34 PromptFinalState photons(Cuts::abspid == PID::PHOTON);
35
36 // Electrons and muons in Fiducial PS
37 PromptFinalState leptons(FinalState(fs_z && (Cuts::abspid == PID::ELECTRON || Cuts::abspid == PID::MUON)));
38 leptons.acceptTauDecays(false);
39 LeptonFinder dressedleptons(leptons, photons, 0.1, FS_Zlept);
40 declare(dressedleptons, "LeptonFinder");
41
42 // Electrons and muons in Total PS
43 PromptFinalState leptons_total(Cuts::abspid == PID::ELECTRON || Cuts::abspid == PID::MUON);
44 leptons_total.acceptTauDecays(false);
45 LeptonFinder dressedleptonsTotal(leptons_total, photons, 0.1);
46 declare(dressedleptonsTotal, "LeptonFinderTotal");
47
48 // Promot neutrinos (yikes!)
49 IdentifiedFinalState nu_id;
50 nu_id.acceptNeutrinos();
51 PromptFinalState neutrinos(nu_id);
52 neutrinos.acceptTauDecays(false);
53 declare(neutrinos, "Neutrinos");
54 MSG_WARNING("\033[91;1mLIMITED VALIDITY - check info file for details!\033[m");
55
56 // Jets
57 VetoedFinalState veto;
58 veto.addVetoOnThisFinalState(dressedleptons);
59 FastJets jets(veto, JetAlg::ANTIKT, 0.4);
60 declare(jets, "Jets");
61
62 // Book histograms
63 book(_h_eee , 1, 1, 1);
64 book(_h_mee , 1, 1, 2);
65 book(_h_emm , 1, 1, 3);
66 book(_h_mmm , 1, 1, 4);
67 book(_h_fid , 1, 1, 5);
68 book(_h_eee_Plus , 2, 1, 1);
69 book(_h_mee_Plus , 2, 1, 2);
70 book(_h_emm_Plus , 2, 1, 3);
71 book(_h_mmm_Plus , 2, 1, 4);
72 book(_h_fid_Plus , 2, 1, 5);
73 book(_h_eee_Minus, 3, 1, 1);
74 book(_h_mee_Minus, 3, 1, 2);
75 book(_h_emm_Minus, 3, 1, 3);
76 book(_h_mmm_Minus, 3, 1, 4);
77 book(_h_fid_Minus, 3, 1, 5);
78 book(_h_total , 6, 1, 1);
79 book(_h_Njets , 8, 1, 1);
80
81 }
82
83
84 void analyze(const Event& event) {
85
86 const DressedLeptons& dressedleptons = apply<LeptonFinder>(event, "LeptonFinder").dressedLeptons();
87 const DressedLeptons& dressedleptonsTotal = apply<LeptonFinder>(event, "LeptonFinderTotal").dressedLeptons();
88 const Particles& neutrinos = apply<PromptFinalState>(event, "Neutrinos").particlesByPt();
89 Jets jets = apply<JetFinder>(event, "Jets").jetsByPt( (Cuts::abseta < 4.5) && (Cuts::pT > 25*GeV) );
90
91 if (dressedleptonsTotal.size() < 3 || neutrinos.size() < 1) vetoEvent;
92
93 //---Total PS: assign leptons to W and Z bosons using Resonant shape algorithm
94 // NB: This resonant shape algorithm assumes the Standard Model and can therefore
95 // NOT be used for any kind of reinterpretation in terms of new-physics models..
96
97 // Try Z pair of leptons 01
98 double MassZ01 = 0, MassW2 = 0;
99 if ( (dressedleptonsTotal[0].pid() ==-(dressedleptonsTotal[1].pid())) && (dressedleptonsTotal[2].abspid()==neutrinos[0].abspid()-1)){
100 MassZ01 = (dressedleptonsTotal[0].momentum()+dressedleptonsTotal[1].momentum()).mass();
101 MassW2 = (dressedleptonsTotal[2].momentum()+neutrinos[0].momentum()).mass();
102 }
103 // Try Z pair of leptons 02
104 double MassZ02 = 0, MassW1 = 0;
105 if ( (dressedleptonsTotal[0].pid()==-(dressedleptonsTotal[2].pid())) && (dressedleptonsTotal[1].abspid()==neutrinos[0].abspid()-1)){
106 MassZ02 = (dressedleptonsTotal[0].momentum()+dressedleptonsTotal[2].momentum()).mass();
107 MassW1 = (dressedleptonsTotal[1].momentum()+neutrinos[0].momentum()).mass();
108 }
109 // Try Z pair of leptons 12
110 double MassZ12 = 0, MassW0 = 0;
111 if ( (dressedleptonsTotal[1].pid()==-(dressedleptonsTotal[2].pid())) && (dressedleptonsTotal[0].abspid()==neutrinos[0].abspid()-1)){
112 MassZ12 = (dressedleptonsTotal[1].momentum()+dressedleptonsTotal[2].momentum()).mass();
113 MassW0 = (dressedleptonsTotal[0].momentum()+neutrinos[0].momentum()).mass();
114 }
115 double WeightZ1 = 1/(pow(MassZ01*MassZ01 - MZ_PDG*MZ_PDG,2) + pow(MZ_PDG*GammaZ_PDG,2));
116 double WeightW1 = 1/(pow(MassW2*MassW2 - MW_PDG*MW_PDG,2) + pow(MW_PDG*GammaW_PDG,2));
117 double WeightTotal1 = WeightZ1*WeightW1;
118 double M1 = -1*WeightTotal1;
119
120 double WeightZ2 = 1/(pow(MassZ02*MassZ02- MZ_PDG*MZ_PDG,2) + pow(MZ_PDG*GammaZ_PDG,2));
121 double WeightW2 = 1/(pow(MassW1*MassW1- MW_PDG*MW_PDG,2) + pow(MW_PDG*GammaW_PDG,2));
122 double WeightTotal2 = WeightZ2*WeightW2;
123 double M2 = -1*WeightTotal2;
124
125 double WeightZ3 = 1/(pow(MassZ12*MassZ12 - MZ_PDG*MZ_PDG,2) + pow(MZ_PDG*GammaZ_PDG,2));
126 double WeightW3 = 1/(pow(MassW0*MassW0 - MW_PDG*MW_PDG,2) + pow(MW_PDG*GammaW_PDG,2));
127 double WeightTotal3 = WeightZ3*WeightW3;
128 double M3 = -1*WeightTotal3;
129
130 int i = -1, j = -1, k = -1;
131 if ((M1 < M2 && M1 < M3) || (MassZ01 != 0 && MassW2 != 0 && MassZ02 == 0 && MassZ12 == 0)) {
132 i = 0; j = 1; k = 2;
133 }
134 if ((M2 < M1 && M2 < M3) || (MassZ02 != 0 && MassW1 != 0 && MassZ01 == 0 && MassZ12 == 0)) {
135 i = 0; j = 2; k = 1;
136 }
137 if ((M3 < M1 && M3 < M2) || (MassZ12 != 0 && MassW0 != 0 && MassZ01 == 0 && MassZ02 == 0)) {
138 i = 1; j = 2; k = 0;
139 }
140 ///
141 if (i < 0 || j < 0 || k < 0) vetoEvent;
142
143 FourMomentum ZbosonTotal = dressedleptonsTotal[i].momentum()+dressedleptonsTotal[j].momentum();
144 if ( ZbosonTotal.mass() >= 66*GeV && ZbosonTotal.mass() <= 116*GeV ) _h_total->fill(13000);
145
146 //---end Total PS
147
148
149 //---Fiducial PS: assign leptons to W and Z bosons using Resonant shape algorithm
150 if (dressedleptons.size() < 3) vetoEvent;
151
152 int EventType = -1;
153 int Nel = 0, Nmu = 0;
154
155 for (const DressedLepton& l : dressedleptons) {
156 if (l.abspid() == 11) ++Nel;
157 if (l.abspid() == 13) ++Nmu;
158 }
159
160 if ( (Nel == 3) && (Nmu==0) ) EventType = 3;
161 if ( (Nel == 2) && (Nmu==1) ) EventType = 2;
162 if ( (Nel == 1) && (Nmu==2) ) EventType = 1;
163 if ( (Nel == 0) && (Nmu==3) ) EventType = 0;
164
165 int EventCharge = -dressedleptons[0].charge() * dressedleptons[1].charge() * dressedleptons[2].charge();
166
167 MassZ01 = 0; MassZ02 = 0; MassZ12 = 0;
168 MassW0 = 0; MassW1 = 0; MassW2 = 0;
169
170 // try Z pair of leptons 01
171 if (dressedleptons[0].pid() == -dressedleptons[1].pid()) {
172 MassZ01 = (dressedleptons[0].momentum() + dressedleptons[1].momentum()).mass();
173 MassW2 = (dressedleptons[2].momentum() + neutrinos[0].momentum()).mass();
174 }
175 // try Z pair of leptons 02
176 if (dressedleptons[0].pid() == -dressedleptons[2].pid()) {
177 MassZ02 = (dressedleptons[0].momentum() + dressedleptons[2].momentum()).mass();
178 MassW1 = (dressedleptons[1].momentum() + neutrinos[0].momentum()).mass();
179 }
180 // try Z pair of leptons 12
181 if (dressedleptons[1].pid() == -dressedleptons[2].pid()) {
182 MassZ12 = (dressedleptons[1].momentum() + dressedleptons[2].momentum()).mass();
183 MassW0 = (dressedleptons[0].momentum() + neutrinos[0].momentum()).mass();
184 }
185 WeightZ1 = 1/(pow(MassZ01*MassZ01 - MZ_PDG*MZ_PDG,2) + pow(MZ_PDG*GammaZ_PDG,2));
186 WeightW1 = 1/(pow(MassW2*MassW2 - MW_PDG*MW_PDG,2) + pow(MW_PDG*GammaW_PDG,2));
187 WeightTotal1 = WeightZ1*WeightW1;
188 M1 = -1*WeightTotal1;
189
190 WeightZ2 = 1/(pow(MassZ02*MassZ02- MZ_PDG*MZ_PDG,2) + pow(MZ_PDG*GammaZ_PDG,2));
191 WeightW2 = 1/(pow(MassW1*MassW1- MW_PDG*MW_PDG,2) + pow(MW_PDG*GammaW_PDG,2));
192 WeightTotal2 = WeightZ2*WeightW2;
193 M2 = -1*WeightTotal2;
194
195 WeightZ3 = 1/(pow(MassZ12*MassZ12 - MZ_PDG*MZ_PDG,2) + pow(MZ_PDG*GammaZ_PDG,2));
196 WeightW3 = 1/(pow(MassW0*MassW0 - MW_PDG*MW_PDG,2) + pow(MW_PDG*GammaW_PDG,2));
197 WeightTotal3 = WeightZ3*WeightW3;
198 M3 = -1*WeightTotal3;
199
200 if( (M1 < M2 && M1 < M3) || (MassZ01 != 0 && MassW2 != 0 && MassZ02 == 0 && MassZ12 == 0) ) {
201 i = 0; j = 1; k = 2;
202 }
203 if((M2 < M1 && M2 < M3) || (MassZ02 != 0 && MassW1 != 0 && MassZ01 == 0 && MassZ12 == 0) ) {
204 i = 0; j = 2; k = 1;
205 }
206 if((M3 < M1 && M3 < M2) || (MassZ12 != 0 && MassW0 != 0 && MassZ01 == 0 && MassZ02 == 0) ) {
207 i = 1; j = 2; k = 0;
208 }
209
210 FourMomentum Zlepton1 = dressedleptons[i].momentum();
211 FourMomentum Zlepton2 = dressedleptons[j].momentum();
212 FourMomentum Wlepton = dressedleptons[k].momentum();
213 FourMomentum Zboson = dressedleptons[i].momentum()+dressedleptons[j].momentum();
214
215 double Wboson_mT = sqrt( 2 * Wlepton.pT() * neutrinos[0].pt() * (1 - cos(deltaPhi(Wlepton, neutrinos[0]))) );
216
217 if (fabs(Zboson.mass()/GeV - MZ_PDG) >= 10.) vetoEvent;
218 if (Wboson_mT <= 30*GeV) vetoEvent;
219 if (Wlepton.pT() <= 20*GeV) vetoEvent;
220 if (deltaR(Zlepton1, Zlepton2) < 0.2) vetoEvent;
221 if (deltaR(Zlepton1, Wlepton) < 0.3) vetoEvent;
222 if (deltaR(Zlepton2, Wlepton) < 0.3) vetoEvent;
223
224 if (EventType == 3) _h_eee->fill(13000.);
225 if (EventType == 2) _h_mee->fill(13000.);
226 if (EventType == 1) _h_emm->fill(13000.);
227 if (EventType == 0) _h_mmm->fill(13000.);
228 _h_fid->fill(13000);
229
230 if (EventCharge == 1) {
231 if (EventType == 3) _h_eee_Plus->fill(13000.);
232 if (EventType == 2) _h_mee_Plus->fill(13000.);
233 if (EventType == 1) _h_emm_Plus->fill(13000.);
234 if (EventType == 0) _h_mmm_Plus->fill(13000.);
235 _h_fid_Plus->fill(13000);
236 } else {
237 if (EventType == 3) _h_eee_Minus->fill(13000.);
238 if (EventType == 2) _h_mee_Minus->fill(13000.);
239 if (EventType == 1) _h_emm_Minus->fill(13000.);
240 if (EventType == 0) _h_mmm_Minus->fill(13000.);
241 _h_fid_Minus->fill(13000);
242 }
243
244 if (jets.size() < 4) _h_Njets->fill(jets.size());
245 else _h_Njets->fill(4);
246
247 }
248
249
250 void finalize() {
251
252 // Print summary info
253 const double xs_pb(crossSection() / picobarn);
254 const double xs_fb(crossSection() / femtobarn);
255 const double sumw(sumOfWeights());
256 const double sf_pb(xs_pb / sumw);
257 const double sf_fb(xs_fb / sumw);
258
259 const float totalBR= 4*0.1086*0.033658; // W and Z leptonic branching fractions
260
261 scale(_h_fid, sf_fb/4.);
262 scale(_h_eee, sf_fb);
263 scale(_h_mee, sf_fb);
264 scale(_h_emm, sf_fb);
265 scale(_h_mmm, sf_fb);
266 scale(_h_fid_Plus, sf_fb/4.);
267 scale(_h_eee_Plus, sf_fb);
268 scale(_h_mee_Plus, sf_fb);
269 scale(_h_emm_Plus, sf_fb);
270 scale(_h_mmm_Plus, sf_fb);
271 scale(_h_fid_Minus, sf_fb/4.);
272 scale(_h_eee_Minus, sf_fb);
273 scale(_h_mee_Minus, sf_fb);
274 scale(_h_emm_Minus, sf_fb);
275 scale(_h_mmm_Minus, sf_fb);
276 scale(_h_Njets, sf_fb/4.);
277 scale(_h_total, sf_pb/totalBR);
278
279 }
280
281 /// @}
282
283
284 private:
285
286
287 /// @name Histograms
288 /// @{
289 Histo1DPtr _h_eee;
290 Histo1DPtr _h_mee;
291 Histo1DPtr _h_emm;
292 Histo1DPtr _h_mmm;
293 Histo1DPtr _h_fid;
294 Histo1DPtr _h_eee_Plus;
295 Histo1DPtr _h_mee_Plus;
296 Histo1DPtr _h_emm_Plus;
297 Histo1DPtr _h_mmm_Plus;
298 Histo1DPtr _h_fid_Plus;
299 Histo1DPtr _h_eee_Minus;
300 Histo1DPtr _h_mee_Minus;
301 Histo1DPtr _h_emm_Minus;
302 Histo1DPtr _h_mmm_Minus;
303 Histo1DPtr _h_fid_Minus;
304 Histo1DPtr _h_total;
305 Histo1DPtr _h_Njets;
306
307 /// @}
308
309 double MZ_PDG = 91.1876;
310 double MW_PDG = 83.385;
311 double GammaZ_PDG = 2.4952;
312 double GammaW_PDG = 2.085;
313
314 };
315
316 RIVET_DECLARE_PLUGIN(ATLAS_2016_I1469071);
317}
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