Rivet analyses referenceCMS_2019_I1753680Measurements of differential Z boson production cross sections in proton-proton collisions at 13 TeVExperiment: CMS (LHC) Inspire ID: 1753680 Status: VALIDATED Authors:
Beam energies: (6500.0, 6500.0) GeV Run details:
Measurements are presented of the differential cross sections for Z bosons produced in proton-proton collisions at $\sqrt{s} = 13 \text{TeV}$ and decaying to muons and electrons. The data analyzed were collected in 2016 with the CMS detector at the LHC and correspond to an integrated luminosity of $35.9/fb$. The measured fiducial inclusive product of cross section and branching fraction agrees with next-to-next-to-leading order quantum chromodynamics calculations. Differential cross sections of the transverse momentum \pt, the optimized angular variable $\phi^{*}_{\eta}$, and the rapidity of lepton pairs are measured. The data are corrected for detector effects and compared to theoretical predictions using fixed order, resummed, and parton shower calculations. The uncertainties of the measured normalized cross sections are smaller than 0.5% for $\phi^{*}_{\eta} < 0.5$ and for $p_{T}^{Z} < 50 \text{GeV}$. Source code: CMS_2019_I1753680.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4#include "Rivet/Projections/FastJets.hh"
5#include "Rivet/Projections/LeptonFinder.hh"
6#include "Rivet/Projections/DileptonFinder.hh"
7
8namespace Rivet {
9
10
11 /// @brief Measurements of differential Z boson production cross sections in proton-proton collisions at 13 TeV
12 class CMS_2019_I1753680 : public Analysis {
13 public:
14
15 /// Constructor
16 RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2019_I1753680);
17
18
19 /// @name Analysis methods
20 /// @{
21
22 /// Book histograms and initialise projections before the run
23 void init() {
24
25 // Get options from the new option system
26 // default to combined.
27 _mode = 2;
28 if ( getOption("LMODE") == "EL" ) _mode = 0;
29 if ( getOption("LMODE") == "MU" ) _mode = 1;
30 if ( getOption("LMODE") == "EMU" ) _mode = 2;
31
32 // Initialise and register projections
33 Cut cut = Cuts::abseta < 2.4 && Cuts::pT > 25*GeV;
34 DileptonFinder zeeFind(91.2*GeV, 0.1, cut && Cuts::abspid == PID::ELECTRON, Cuts::massIn(76.2*GeV, 106.2*GeV));
35 declare(zeeFind, "ZeeFind");
36 DileptonFinder zmmFind(91.2*GeV, 0.1, cut && Cuts::abspid == PID::MUON , Cuts::massIn(76.2*GeV, 106.2*GeV));
37 declare(zmmFind, "ZmmFind");
38
39 // Book histograms
40 book(_h_Zmm_absY, 26, 1, 1);
41 book(_h_Zee_absY, 26, 1, 2);
42 book(_h["absY"], 26, 1, 3);
43 book(_h_Zmm_pt, 27, 1, 1);
44 book(_h_Zee_pt, 27, 1, 2);
45 book(_h["pt"], 27, 1, 3);
46 book(_h_Zmm_phiStar, 28, 1, 1);
47 book(_h_Zee_phiStar, 28, 1, 2);
48 book(_h["phiStar"], 28, 1, 3);
49 book(_h["pt_Y0"], 29, 1, 1);
50 book(_h["pt_Y1"], 29, 1, 2);
51 book(_h["pt_Y2"], 29, 1, 3);
52 book(_h["pt_Y3"], 29, 1, 4);
53 book(_h["pt_Y4"], 29, 1, 5);
54
55 book(_h_norm["pt"], 30, 1, 1);
56 book(_h_norm["phiStar"], 31, 1, 1);
57 book(_h_norm["absY"], 32, 1, 1);
58 book(_h_norm["pt_Y0"], 33, 1, 1);
59 book(_h_norm["pt_Y1"], 33, 1, 2);
60 book(_h_norm["pt_Y2"], 33, 1, 3);
61 book(_h_norm["pt_Y3"], 33, 1, 4);
62 book(_h_norm["pt_Y4"], 33, 1, 5);
63
64 }
65
66
67 /// Perform the per-event analysis
68 void analyze(const Event& event) {
69
70 const DileptonFinder& zeeFS = apply<DileptonFinder>(event, "ZeeFind");
71 const DileptonFinder& zmumuFS = apply<DileptonFinder>(event, "ZmmFind");
72
73 const Particles& zees = zeeFS.bosons();
74 const Particles& zmumus = zmumuFS.bosons();
75
76 if (zees.size() + zmumus.size() != 1) {
77 MSG_DEBUG("Did not find exactly one good Z candidate");
78 vetoEvent;
79 }
80
81 //event identification depending on mass window
82 bool ee_event=false;
83 bool mm_event=false;
84
85 if (zees.size() == 1) {
86 ee_event = true;
87 }
88 if (zmumus.size() == 1) {
89 mm_event = true;
90 }
91
92 if (ee_event && _mode == 1)
93 vetoEvent;
94 if (mm_event && _mode == 0)
95 vetoEvent;
96
97 const Particles& theLeptons = ee_event ? zeeFS.constituents() : zmumuFS.constituents();
98 const Particle& lminus = theLeptons[0].charge() < 0 ? theLeptons[0] : theLeptons[1];
99 const Particle& lplus = theLeptons[0].charge() < 0 ? theLeptons[1] : theLeptons[0];
100
101 //calculate phi*
102 const double thetaStar = acos(tanh( 0.5 * (lminus.eta() - lplus.eta()) ));
103 const double dPhi = M_PI - deltaPhi(lminus, lplus);
104 const double phiStar = tan(0.5 * dPhi) * sin(thetaStar);
105
106 const Particle& zcand = ee_event ? zees[0] : zmumus[0];
107
108 if (ee_event) {
109 _h_Zee_absY->fill(zcand.absrap());
110 _h_Zee_pt->fill(zcand.pt()/GeV);
111 _h_Zee_phiStar->fill(phiStar);
112 }
113 else if (mm_event) {
114 _h_Zmm_absY->fill(zcand.absrap());
115 _h_Zmm_pt->fill(zcand.pt()/GeV);
116 _h_Zmm_phiStar->fill(phiStar);
117 }
118
119 _h["pt"]->fill(zcand.pt()/GeV);
120 _h_norm["pt"]->fill(zcand.pt()/GeV);
121 _h["phiStar"]->fill(phiStar);
122 _h_norm["phiStar"]->fill(phiStar);
123 _h["absY"]->fill(zcand.absrap());
124 _h_norm["absY"]->fill(zcand.absrap());
125
126 if (zcand.absrap() < 0.4) {
127 _h["pt_Y0"]->fill(zcand.pt()/GeV);
128 _h_norm["pt_Y0"]->fill(zcand.pt()/GeV);
129 }
130 else if (zcand.absrap() < 0.8) {
131 _h["pt_Y1"]->fill(zcand.pt()/GeV);
132 _h_norm["pt_Y1"]->fill(zcand.pt()/GeV);
133 }
134 else if (zcand.absrap() < 1.2) {
135 _h["pt_Y2"]->fill(zcand.pt()/GeV);
136 _h_norm["pt_Y2"]->fill(zcand.pt()/GeV);
137 }
138 else if (zcand.absrap() < 1.6) {
139 _h["pt_Y3"]->fill(zcand.pt()/GeV);
140 _h_norm["pt_Y3"]->fill(zcand.pt()/GeV);
141 }
142 else if (zcand.absrap() < 2.4) {
143 _h["pt_Y4"]->fill(zcand.pt()/GeV);
144 _h_norm["pt_Y4"]->fill(zcand.pt()/GeV);
145 }
146
147 }
148
149 /// Normalise histograms etc., after the run
150 void finalize() {
151
152 double norm = (sumOfWeights() != 0) ? crossSection()/picobarn/sumOfWeights() : 1.0;
153
154 scale(_h_Zmm_pt, norm);
155 scale(_h_Zmm_absY, norm);
156 scale(_h_Zmm_phiStar, norm);
157
158 scale(_h_Zee_pt, norm);
159 scale(_h_Zee_absY, norm);
160 scale(_h_Zee_phiStar, norm);
161
162 // when running in combined mode, need to average to get lepton xsec
163 if (_mode == 2) norm /= 2.;
164 scale(_h, norm);
165
166 for (auto& item : _h_norm) {
167 const double rho = item.second->densitySum(false);
168 if (rho) scale(item.second, 1.0/rho);
169 }
170
171 }
172
173 /// @}
174
175 protected:
176
177 size_t _mode;
178
179 /// @name Histograms
180
181 private:
182
183 Histo1DPtr _h_Zmm_pt, _h_Zmm_phiStar, _h_Zmm_absY;
184 Histo1DPtr _h_Zee_pt, _h_Zee_phiStar, _h_Zee_absY;
185
186 map<string,Histo1DPtr> _h;
187 map<string,Histo1DPtr> _h_norm;
188
189 };
190
191
192 RIVET_DECLARE_PLUGIN(CMS_2019_I1753680);
193
194
195}
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