1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/VetoedFinalState.hh"
#include "Rivet/Projections/InvMassFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include <algorithm>
namespace Rivet {
/// @brief CDF jet pT and multiplicity distributions in W + jets events
///
/// This CDF analysis provides jet pT distributions for 4 jet multiplicity bins
/// as well as the jet multiplicity distribution in W + jets events.
class CDF_2008_S7541902 : public Analysis {
public:
RIVET_DEFAULT_ANALYSIS_CTOR(CDF_2008_S7541902);
/// @name Analysis methods
//@{
void init() {
// Set up projections
// Basic FS
FinalState fs((Cuts::etaIn(-3.6, 3.6)));
declare(fs, "FS");
// Create a final state with any e-nu pair with invariant mass 65 -> 95 GeV and ET > 20 (W decay products)
vector<pair<PdgId,PdgId> > vids;
vids += make_pair(PID::ELECTRON, PID::NU_EBAR);
vids += make_pair(PID::POSITRON, PID::NU_E);
FinalState fs2((Cuts::etaIn(-3.6, 3.6) && Cuts::pT >= 20*GeV));
InvMassFinalState invfs(fs2, vids, 65*GeV, 95*GeV);
declare(invfs, "INVFS");
// Make a final state without the W decay products for jet clustering
VetoedFinalState vfs(fs);
vfs.addVetoOnThisFinalState(invfs);
declare(vfs, "VFS");
declare(FastJets(vfs, FastJets::CDFJETCLU, 0.4), "Jets");
// Book histograms
for (int i = 0 ; i < 4 ; ++i) {
book(_histJetEt[i] ,1+i, 1, 1);
book(_histJetMultRatio[i], 5, 1, i+1, true);
/// @todo These would be better off as YODA::Counter until finalize()
book(_histJetMult[i] ,6+i, 1, 1); // _sumW is essentially the 0th "histo" counter
}
book(_sumW,"sumW");
}
/// Do the analysis
void analyze(const Event& event) {
// Get the W decay products (electron and neutrino)
const InvMassFinalState& invMassFinalState = apply<InvMassFinalState>(event, "INVFS");
const Particles& wDecayProducts = invMassFinalState.particles();
FourMomentum electronP, neutrinoP;
bool gotElectron(false), gotNeutrino(false);
for (const Particle& p : wDecayProducts) {
FourMomentum p4 = p.momentum();
if (p4.Et() > _electronETCut && fabs(p4.eta()) < _electronETACut && p.abspid() == PID::ELECTRON) {
electronP = p4;
gotElectron = true;
}
else if (p4.Et() > _eTmissCut && p.abspid() == PID::NU_E) {
neutrinoP = p4;
gotNeutrino = true;
}
}
// Veto event if the electron or MET cuts fail
if (!gotElectron || !gotNeutrino) vetoEvent;
// Veto event if the MTR cut fails
double mT2 = 2.0 * ( electronP.pT()*neutrinoP.pT() - electronP.px()*neutrinoP.px() - electronP.py()*neutrinoP.py() );
if (sqrt(mT2) < _mTCut ) vetoEvent;
// Get the jets
const JetAlg& jetProj = apply<FastJets>(event, "Jets");
Jets theJets = jetProj.jets(cmpMomByEt, Cuts::Et > _jetEtCutA);
size_t njetsA(0), njetsB(0);
for (const Jet& j : theJets) {
const FourMomentum pj = j.momentum();
if (fabs(pj.rapidity()) < _jetETA) {
// Fill differential histograms for top 4 jets with Et > 20
if (njetsA < 4 && pj.Et() > _jetEtCutA) {
++njetsA;
_histJetEt[njetsA-1]->fill(pj.Et());
}
// Count number of jets with Et > 25 (for multiplicity histograms)
if (pj.Et() > _jetEtCutB) ++njetsB;
}
}
// Increment event counter
_sumW->fill();
// Jet multiplicity
for (size_t i = 1; i <= njetsB; ++i) {
/// @todo This isn't really a histogram: replace with a YODA::Counter when we have one!
_histJetMult[i-1]->fill(1960.);
if (i == 4) break;
}
}
/// Finalize
void finalize() {
// Fill the 0th ratio histogram specially
/// @todo This special case for 1-to-0 will disappear if we use Counters for all mults including 0.
if (_sumW->val() > 0) {
const YODA::Histo1D::Bin& b0 = _histJetMult[0]->bin(0);
double ratio = b0.area()/dbl(*_sumW);
double frac_err = 1/dbl(*_sumW); ///< This 1/sqrt{N} error treatment isn't right for weighted events: use YODA::Counter
if (b0.area() > 0) frac_err = sqrt( sqr(frac_err) + sqr(b0.areaErr()/b0.area()) );
_histJetMultRatio[0]->point(0).setY(ratio, ratio*frac_err);
}
// Loop over the non-zero multiplicities
for (size_t i = 0; i < 3; ++i) {
const YODA::Histo1D::Bin& b1 = _histJetMult[i]->bin(0);
const YODA::Histo1D::Bin& b2 = _histJetMult[i+1]->bin(0);
if (b1.area() == 0.0) continue;
double ratio = b2.area()/b1.area();
double frac_err = b1.areaErr()/b1.area();
if (b2.area() > 0) frac_err = sqrt( sqr(frac_err) + sqr(b2.areaErr()/b2.area()) );
_histJetMultRatio[i+1]->point(0).setY(ratio, ratio*frac_err);
}
// Normalize the non-ratio histograms
for (size_t i = 0; i < 4; ++i) {
scale(_histJetEt[i], crossSection()/picobarn/sumOfWeights());
scale(_histJetMult[i], crossSection()/picobarn/sumOfWeights());
}
}
//@}
private:
/// @name Cuts
//@{
/// Cut on the electron ET:
double _electronETCut = 20*GeV;
/// Cut on the electron ETA:
double _electronETACut = 1.1;
/// Cut on the missing ET
double _eTmissCut = 30*GeV;
/// Cut on the transverse mass squared
double _mTCut = 20*GeV;
/// Cut on the jet ET for differential cross sections
double _jetEtCutA = 20*GeV;
/// Cut on the jet ET for jet multiplicity
double _jetEtCutB = 25*GeV;
/// Cut on the jet ETA
double _jetETA = 2.0;
//@}
/// @name Histograms
//@{
Histo1DPtr _histJetEt[4];
Histo1DPtr _histJetMultNorm;
Scatter2DPtr _histJetMultRatio[4];
Histo1DPtr _histJetMult[4];
CounterPtr _sumW;
//@}
};
RIVET_DECLARE_ALIASED_PLUGIN(CDF_2008_S7541902, CDF_2008_I768579);
}
|