Rivet analyses referenceATLAS_2016_I1502620W and Z inclusive cross sections at 7 TeVExperiment: ATLAS (LHC) Inspire ID: 1502620 Status: VALIDATED Authors:
Beam energies: (3500.0, 3500.0) GeV Run details:
High-precision measurements by the ATLAS Collaboration are presented of inclusive $W^+\to\ell^+$, $W^-\to\ell^-$, $Z/\gamma^\ast\to\ell\ell$ ($\ell=e,\mu$) Drell-Yan production cross sections at the LHC. The data were collected in proton-proton collisions at $\sqrt{s}=7$ TeV with an integrated luminosity of 4.6 fb${}^{-1}$. Differential $W^+$ and $W^-$ cross sections are measured in a lepton pseudorapidity range $|\eta_\ell| < 2.5$. Differential $Z/\gamma^\ast$ cross sections are measured as a function of the absolute dilepton rapidity, for $|y_{\ell\ell}| < 3.6$, for three intervals of dilepton mass, $m_{\ell\ell}$, extending from 46 to 150 GeV. The integrated and differential electron- and muon-channel cross sections are combined and compared to theoretical predictions using recent sets of parton distribution functions. The data, together with the final inclusive $e^\pm p$ scattering cross-section data from H1 and ZEUS, are interpreted in a next-to-next-to-leading-order QCD analysis, and a new set of parton distribution functions, ATLAS-epWZ16, is obtained. The ratio of strange-to-light sea-quark densities in the proton is determined more accurately than in previous determinations based on collider data only, and is established to be close to unity in the sensitivity range of the data. A new measurement of the CKM matrix element $|V_{cs}|$ is also provided. N.B.: Use :LMODE to choose specify the signature decay channel directly. Default, run everything, assuming all decay modes are generated Contains Z (W): fill only Z (W) signature histograms Contains EL (MU): assume only electron (muon) decay modes are being generated. Source code: ATLAS_2016_I1502620.cc 1#include "Rivet/Analysis.hh"
2#include "Rivet/Projections/FinalState.hh"
3#include "Rivet/Projections/MissingMomentum.hh"
4#include "Rivet/Projections/LeptonFinder.hh"
5#include "Rivet/Projections/DileptonFinder.hh"
6
7namespace Rivet {
8
9
10 /// @brief inclusive W/Z cross sections at 7 TeV
11 class ATLAS_2016_I1502620 : public Analysis {
12 public:
13
14 /// Constructor
15 RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2016_I1502620);
16
17
18 /// @name Analysis methods
19 /// @{
20
21 /// Book histograms and initialise projections before the run
22 void init() {
23
24 // Get options from the option system
25 _mode = 0;
26 _runZ = true;
27 _runW = true;
28 if ( getOption("LMODE") == "EL" ||
29 getOption("LMODE") == "ZEL" ||
30 getOption("LMODE") == "WEL" )
31 _mode = 1;
32 if ( getOption("LMODE") == "MU" ||
33 getOption("LMODE") == "ZMU" ||
34 getOption("LMODE") == "WMU" )
35 _mode = 2;
36 if ( getOption("LMODE") == "Z" ||
37 getOption("LMODE") == "ZEL" ||
38 getOption("LMODE") == "ZMU" )
39 _runW = false;
40 if ( getOption("LMODE") == "W" ||
41 getOption("LMODE") == "WEL" ||
42 getOption("LMODE") == "WMU" )
43 _runZ = false;
44
45
46 // Initialise and register projections
47 declare("MET", MissingMomentum());
48 LeptonFinder ef(0.1, Cuts::pT > 25*GeV && Cuts::abspid == PID::ELECTRON);
49 declare(ef, "Elecs");
50 LeptonFinder mf(0.1, Cuts::pT > 25*GeV && Cuts::abspid == PID::MUON);
51 declare(mf, "Muons");
52
53 DileptonFinder zfe(91.2*GeV, 0.1, Cuts::pT > 20*GeV && Cuts::abspid == PID::ELECTRON, Cuts::massIn(46.0*GeV, 150*GeV));
54 declare(zfe, "Zee");
55 DileptonFinder zfm(91.2*GeV, 0.1, Cuts::pT > 20*GeV && Cuts::abspid == PID::MUON, Cuts::massIn(46.0*GeV, 150*GeV));
56 declare(zfm, "Zmm");
57
58
59 // Book histograms
60 if (_runW) {
61 book(_h_Wp_eta, 9, 1, 1);
62 book(_h_Wm_eta, 10, 1, 1);
63 book(_h_W_asym, 35, 1, 1);
64 }
65 if (_runZ) {
66 book(_h_Zcenlow_y_dressed, 11, 1, 1);
67 book(_h_Zcenpeak_y_dressed, 12, 1, 1);
68 book(_h_Zcenhigh_y_dressed, 13, 1, 1);
69 book(_h_Zfwdpeak_y_dressed, 14, 1, 1);
70 book(_h_Zfwdhigh_y_dressed, 15, 1, 1);
71 }
72 }
73
74
75 /// Perform the per-event analysis
76 void analyze(const Event& event) {
77
78 // W reco, starting with MET
79 const P4& pmiss = apply<MissingMom>(event, "MET").missingMom();
80
81 // Identify the closest-matching l+MET to m == mW
82 const Particles& es = apply<LeptonFinder>(event, "Elecs").particles();
83 const Particles es_mtfilt = select(es, [&](const Particle& e){ return mT(e, pmiss) > 40*GeV; });
84 const int iefound = closestMatchIndex(es_mtfilt, pmiss, Kin::mass, 80.4*GeV);
85 const Particles& mus = apply<LeptonFinder>(event, "Muons").particles();
86 const Particles mus_mtfilt = select(mus, [&](const Particle& m){ return mT(m, pmiss) > 40*GeV; });
87 const int imfound = closestMatchIndex(mus_mtfilt, pmiss, Kin::mass, 80.4*GeV);
88
89 // Require only one W candidate
90 if (pmiss.pT() > 25*GeV && (int(iefound >= 0) + int(imfound >= 0)) == 1 && _runW) {
91 Particle lep;
92 if (_mode != 2 && iefound >= 0) lep = es_mtfilt[iefound];
93 else if (_mode != 1 && imfound >= 0) lep = mus_mtfilt[imfound];
94
95 if (lep.charge3() == 3) _h_Wp_eta->fill(lep.abseta());
96 else if (lep.charge3() == -3) _h_Wm_eta->fill(lep.abseta());
97 }
98
99
100 // Now the Z stuff.
101 const DileptonFinder& zee = apply<DileptonFinder>(event, "Zee");
102 const DileptonFinder& zmm = apply<DileptonFinder>(event, "Zmm");
103 if ((zee.bosons().size() + zmm.bosons().size()) == 1 && _runZ) {
104 Particle zboson;
105 if (_mode != 2 && zee.bosons().size() == 1) zboson = zee.boson();
106 else if (_mode !=1 && zmm.bosons().size() == 1 ) zboson = zmm.boson();
107
108 const Particles& leptons = zboson.constituents();
109 if (leptons.size() > 1) {
110 const double zrap = zboson.absrap();
111 const double zmass = zboson.mass();
112 const double eta1 = leptons[0].abseta();
113 const double eta2 = leptons[1].abseta();
114
115 // Separation into central/forward and three mass bins
116 if (eta1 < 2.5 && eta2 < 2.5) {
117 if (zmass < 66.0*GeV) _h_Zcenlow_y_dressed->fill(zrap);
118 else if (zmass < 116.0*GeV) _h_Zcenpeak_y_dressed->fill(zrap);
119 else _h_Zcenhigh_y_dressed->fill(zrap);
120 }
121 else if ((eta1 < 2.5 && 2.5 < eta2 && eta2 < 4.9) || (eta2 < 2.5 && 2.5 < eta1 && eta1 < 4.9)) {
122 if (zmass > 66.0*GeV) {
123 if (zmass < 116.0*GeV) _h_Zfwdpeak_y_dressed->fill(zrap);
124 else _h_Zfwdhigh_y_dressed->fill(zrap);
125 }
126 }
127 }
128 }
129 }
130
131
132 /// Normalise histograms etc., after the run
133 void finalize() {
134
135 // Construct asymmetry: (dsig+/deta - dsig-/deta) / (dsig+/deta + dsig-/deta)
136 if (_runW) asymm(_h_Wp_eta, _h_Wm_eta, _h_W_asym);
137
138 /// Normalise, scale and otherwise manipulate histograms here
139 double lfac = 1.0;
140 // If we running on both electrons and muons, divide by two -> xsec for one flavour
141 if (_mode == 0) lfac = 0.5;
142 const double sf = lfac * 0.5 * crossSection() /picobarn / sumOfWeights(); //< 0.5 accounts for folding +/- rapidity
143
144 if (_runW){
145 scale(_h_Wp_eta, sf);
146 scale(_h_Wm_eta, sf);
147 }
148
149 if (_runZ){
150 scale(_h_Zcenlow_y_dressed, sf);
151 scale(_h_Zcenpeak_y_dressed, sf);
152 scale(_h_Zcenhigh_y_dressed, sf);
153 scale(_h_Zfwdpeak_y_dressed, sf);
154 scale(_h_Zfwdhigh_y_dressed, sf);
155 }
156 }
157
158 /// @}
159
160
161 protected:
162
163 size_t _mode;
164 bool _runZ, _runW;
165
166
167 private:
168
169 /// @name Histograms
170 /// @{
171 Histo1DPtr _h_Wp_eta, _h_Wm_eta;
172 Estimate1DPtr _h_W_asym;
173
174 Histo1DPtr _h_Zcenlow_y_dressed;
175 Histo1DPtr _h_Zcenpeak_y_dressed;
176 Histo1DPtr _h_Zcenhigh_y_dressed;
177 Histo1DPtr _h_Zfwdpeak_y_dressed;
178 Histo1DPtr _h_Zfwdhigh_y_dressed;
179 /// @}
180
181 };
182
183
184 RIVET_DECLARE_PLUGIN(ATLAS_2016_I1502620);
185
186}
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