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
| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/IdentifiedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
namespace Rivet {
class ATLAS_2014_I1307756 : public Analysis {
public:
/// Constructor
ATLAS_2014_I1307756()
: Analysis("ATLAS_2014_I1307756")
{ }
/// @name Analysis methods
//@{
/// Book histograms and initialise projections before the run
void init() {
/// Initialise and register projections here
FinalState fs;
declare(fs, "FS");
FastJets fj(fs, FastJets::KT, 0.5);
fj.useJetArea(new fastjet::AreaDefinition(fastjet::VoronoiAreaSpec()));
declare(fj, "KtJetsD05");
IdentifiedFinalState photonfs(Cuts::abseta < 2.37 && Cuts::pT > 22*GeV);
photonfs.acceptId(PID::PHOTON);
declare(photonfs, "photons");
// Initialize event count here:
book(_fidWeights, "_fidWeights");
}
int getEtaBin(double eta) const {
double aeta = fabs(eta);
return binIndex(aeta, _eta_bins_areaoffset);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
/// Require at least 2 photons in final state
Particles photons = apply<IdentifiedFinalState>(event, "photons").particlesByPt();
if (photons.size() < 2) vetoEvent;
// Get jet pT densities
vector< vector<double> > ptDensities(_eta_bins_areaoffset.size()-1);
const auto clust_seq_area = apply<FastJets>(event, "KtJetsD05").clusterSeqArea();
for (const Jet& jet : apply<FastJets>(event, "KtJetsD05").jets()) {
const double area = clust_seq_area->area(jet);
if (area > 1e-4 && jet.abseta() < _eta_bins_areaoffset.back()) {
ptDensities.at(getEtaBin(jet.abseta())) += jet.pT()/area;
}
}
/// Compute the median energy density per eta bin
vector<double> ptDensity;
for (size_t b = 0; b < _eta_bins_areaoffset.size()-1; ++b) {
ptDensity += ptDensities[b].empty() ? 0 : median(ptDensities[b]);
}
// Loop over photons and find isolated ones
Particles isolated_photons;
for (const Particle& ph : photons) {
Particles fs = apply<FinalState>(event, "FS").particles();
FourMomentum mom_in_EtCone;
for (const Particle& p : fs) {
// Reject if the particle is not in DR=0.4 cone
if (deltaR(ph.momentum(), p.momentum()) > 0.4) continue;
// Reject if the particle falls in the photon core
if (fabs(ph.eta() - p.eta()) < 0.025 * 7 * 0.5 &&
fabs(ph.phi() - p.phi()) < PI/128. * 5 * 0.5) continue;
// Reject if the particle is a neutrino (muons are kept)
if (p.isNeutrino()) continue;
// Sum momenta
mom_in_EtCone += p.momentum();
}
// Subtract the UE correction (area*density)
const double ETCONE_AREA = M_PI*.4*.4 - (7.0*.025)*(5.0*M_PI/128.);
const double correction = ptDensity[getEtaBin(ph.eta())] * ETCONE_AREA;
// Add isolated photon to list
if (mom_in_EtCone.Et() - correction > 12*GeV) continue;
isolated_photons.push_back(ph);
}
// Require at least two isolated photons
if (isolated_photons.size() < 2) vetoEvent ;
// Select leading pT pair
std::sort(isolated_photons.begin(), isolated_photons.end(), cmpMomByPt);
const FourMomentum& y1 = isolated_photons[0].momentum();
const FourMomentum& y2 = isolated_photons[1].momentum();
// Compute invariant mass
const FourMomentum yy = y1 + y2;
const double Myy = yy.mass();
// If Myy >= 110 GeV, apply relative cuts
if (Myy >= 110*GeV && (y1.Et()/Myy < 0.4 || y2.Et()/Myy < 0.3) ) vetoEvent;
// Add to cross-section
_fidWeights->fill();
}
void finalize() {
scale(_fidWeights, crossSectionPerEvent()/femtobarn);
}
//@}
private:
const vector<double> _eta_bins_areaoffset = {0.0, 1.5, 3.0};
CounterPtr _fidWeights;
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(ATLAS_2014_I1307756);
}
|