Rivet analyses
EW Zjj using early Run-2 data
Experiment: ATLAS (LHC)
Inspire ID: 1627873
Status: VALIDATED
Authors: - Christian Johnson - Deepak Kar - Christian Gutschow
References: - Expt page: ATLAS-STDM-2016-09 - JHEP 1404 (2014) 031 - arXiv: 1709.10264
Beams: p+ p+
Beam energies: (6500.0, 6500.0)GeV
Run details: - Inclusive Z+jets events at 13 TeV, with Z decaying to muons or electrons
The cross-section for the production of two jets in association with a leptonically decaying Z boson (Zjj) is measured in proton-proton collisions at a centre-of-mass energy of 13 TeV, using data recorded with the ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of 3.2 fb−1. The electroweak Zjj cross-section is extracted in a fiducial region chosen to enhance the electroweak contribution relative to the dominant Drell-Yan Zjj process, which is constrained using a data-driven approach. The measured fiducial electroweak cross-section is σEWZjj = 119$16(stat.)20(syst.)2(lumi.)fbfordijetinvariantmassgreaterthan250GeV, and34.25.8(stat.)5.5(syst.)$0.7(lumi.) fb for dijet invariant mass greater than 1 TeV. Standard Model predictions are in agreement with the measurements. The inclusive Zjj cross-section is also measured in six different fiducial regions with varying contributions from electroweak and Drell-Yan Zjj production.
Source
code:ATLAS_2017_I1627873.cc
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/LeptonFinder.hh"
#include "Rivet/Projections/PromptFinalState.hh"
#include "Rivet/Projections/VetoedFinalState.hh"
namespace Rivet {
/// @brief EW Zjj using early Run-2 data
class ATLAS_2017_I1627873 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2017_I1627873);
/// Book histograms and initialise projections before the run
void init() {
_mode = 0;
if (getOption("TYPE") == "EW_ONLY") _mode = 1;
FinalState fs(Cuts::abseta < 5.0);
FinalState photon_fs(Cuts::abspid == PID::PHOTON);
PromptFinalState electron_fs(Cuts::abspid == PID::ELECTRON);
PromptFinalState muon_fs(Cuts::abspid == PID::MUON);
LeptonFinder dressed_electrons(electron_fs, photon_fs, 0.1, Cuts::abseta < 2.47 && Cuts::pT > 25 * GeV);
declare(dressed_electrons, "DressedElectrons");
LeptonFinder dressed_muons(muon_fs, photon_fs, 0.1, Cuts::abseta < 2.47 && Cuts::pT > 25 * GeV);
declare(dressed_muons, "DressedMuons");
VetoedFinalState remfs(fs);
remfs.addVetoOnThisFinalState(dressed_electrons);
remfs.addVetoOnThisFinalState(dressed_muons);
FastJets jets(remfs, JetAlg::ANTIKT, 0.4, JetMuons::ALL, JetInvisibles::ALL);
declare(jets, "Jets");
if (_mode)
book(_h, 3, 1, 1);
else
book(_h, 2, 1, 1);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
const Jets& jets = apply<FastJets>(event, "Jets").jetsByPt(Cuts::pT > 25 * GeV && Cuts::abseta < 4.4);
DressedLeptons electrons = apply<LeptonFinder>(event, "DressedElectrons").dressedLeptons();
DressedLeptons muons = apply<LeptonFinder>(event, "DressedMuons").dressedLeptons();
// Overlap Removal
idiscardIfAnyDeltaRLess(electrons, jets, 0.4);
idiscardIfAnyDeltaRLess(muons, jets, 0.4);
Particle lep1, lep2;
if (electrons.size() == 2 && muons.empty()) {
lep1 = electrons[0];
lep2 = electrons[1];
if (lep1.charge3() == lep2.charge3()) vetoEvent;
}
else if (electrons.empty() && muons.size() == 2) {
lep1 = muons[0];
lep2 = muons[1];
if (lep1.charge3() == lep2.charge3()) vetoEvent;
}
else
vetoEvent;
if (jets.size() < 2) vetoEvent;
const FourMomentum dilepton = lep1.mom() + lep2.mom();
if (!inRange(dilepton.mass(), 81.0 * GeV, 101.0 * GeV)) vetoEvent;
const double jet1pt = jets[0].pT();
const double jet2pt = jets[1].pT();
const double mjj = (jets[0].mom() + jets[1].mom()).mass();
const double zpt = (lep1.mom() + lep2.mom()).pT();
size_t ngapjets = 0;
Jet thirdjet;
for (size_t i = 2; i < jets.size(); ++i) {
const Jet j = jets[i];
if (_isBetween(j, jets[0], jets[1])) {
if (!ngapjets) thirdjet = j;
++ngapjets;
}
}
const double ptbal_vec = (jets[0].mom() + jets[1].mom() + lep1.mom() + lep2.mom()).pT();
const double ptbal_sc = jets[0].pT() + jets[1].pT() + lep1.pT() + lep2.pT();
const double ptbalance2 = ptbal_vec / ptbal_sc;
const double ptbal3_vec = (jets[0].mom() + jets[1].mom() + thirdjet.mom() + lep1.mom() + lep2.mom())
.pT();
const double ptbal3_sc = jets[0].pT() + jets[1].pT() + thirdjet.pT() + lep1.pT() + lep2.pT();
const double ptbalance3 = ptbal3_vec / ptbal3_sc;
//categories: baseline, high-PT, EW-enriched, QCD-enriched, high-mass, EW-enriched and high-mass
if (!(jet1pt > 55 * GeV && jet2pt > 45 * GeV)) vetoEvent;
if (_mode) {
if (zpt > 20.0 * GeV && !ngapjets && ptbalance2 < 0.15 && mjj > 250.0 * GeV) {
_h->fill(_h->bin(1).xEdge());
}
if (zpt > 20.0 * GeV && !ngapjets && ptbalance2 < 0.15 && mjj > 1000.0 * GeV) {
_h->fill(_h->bin(2).xEdge());
}
}
else {
_h->fill(_h->bin(1).xEdge());
if (jet1pt > 85.0 * GeV && jet2pt > 75.0 * GeV) _h->fill(_h->bin(2).xEdge());
if (zpt > 20.0 * GeV && ngapjets == 0 && ptbalance2 < 0.15 && mjj > 250.0 * GeV)
_h->fill(_h->bin(3).xEdge());
if (zpt > 20.0 * GeV && ngapjets && ptbalance3 < 0.15 && mjj > 250.0 * GeV)
_h->fill(_h->bin(4).xEdge());
if (mjj > 1000.0 * GeV) _h->fill(_h->bin(5).xEdge());
if (zpt > 20.0 * GeV && !ngapjets && ptbalance2 < 0.15 && mjj > 1000.0 * GeV)
_h->fill(_h->bin(3).xEdge());
}
}
/// Normalise histograms etc., after the run
void finalize() {
const double factor = crossSection() / (_mode ? femtobarn : picobarn) / sumOfWeights();
scale(_h, factor);
}
bool _isBetween(const Jet probe, const Jet boundary1, const Jet boundary2) {
double y_p = probe.rapidity();
double y_b1 = boundary1.rapidity();
double y_b2 = boundary2.rapidity();
double y_min = std::min(y_b1, y_b2);
double y_max = std::max(y_b1, y_b2);
if (y_p > y_min && y_p < y_max)
return true;
else
return false;
}
///@}
private:
size_t _mode;
/// @name Histograms
///@{
BinnedHistoPtr<string> _h;
///@}
};
RIVET_DECLARE_PLUGIN(ATLAS_2017_I1627873);
}