Rivet analyses
Higgs-to-WW differential cross sections at 8 TeV
Experiment: ATLAS (LHC)
Inspire ID: 1444991
Status: VALIDATED
Authors: - Kathrin Becker
References: - Expt page: ATLAS-HIGG-2015-04 - JHEP 1608 (2016) 104 - DOI: 10.1007/JHEP08(2016)104 - arXiv: 1604.02997
Beams: p+ p+
Beam energies: (4000.0, 4000.0)GeV
Run details: - gg -> H -> W W* -> enu munu production at 8 TeV
This paper describes a measurement of fiducial and differential cross sections of gluon-fusion Higgs boson production in the H → WW* → eνμν channel, using 20.3 fb−1 of proton-proton collision data. The data were produced at a centre-of-mass energy of $\sqrt{s} = 8$ TeV at the CERN Large Hadron Collider and recorded by the ATLAS detector in 2012. Cross sections are measured from the observed H → WW* → eνμν signal yield in categories distinguished by the number of associated jets. The total cross section is measured in a fiducial region defined by the kinematic properties of the charged leptons and neutrinos. Differential cross sections are reported as a function of the number of jets, the Higgs boson transverse momentum, the dilepton rapidity, and the transverse momentum of the leading jet. The jet-veto efficiency, or fraction of events with no jets above a given transverse momentum threshold, is also reported. All measurements are compared to QCD predictions from Monte Carlo generators and fixed-order calculations, and are in agreement with the Standard Model predictions.
Source
code:ATLAS_2016_I1444991.cc
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/LeptonFinder.hh"
#include "Rivet/Projections/IdentifiedFinalState.hh"
#include "Rivet/Projections/PromptFinalState.hh"
#include "Rivet/Projections/VetoedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/VisibleFinalState.hh"
namespace Rivet {
/// Higgs-to-WW differential cross sections at 8 TeV
class ATLAS_2016_I1444991 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2016_I1444991);
/// Book histograms and initialise projections before the run
void init() {
// All particles within |eta| < 5.0
const FinalState FS(Cuts::abseta < 5.0);
// Project photons for dressing
IdentifiedFinalState photon_id(FS);
photon_id.acceptIdPair(PID::PHOTON);
// Project dressed electrons with pT > 15 GeV and |eta| < 2.47
IdentifiedFinalState el_id(FS);
el_id.acceptIdPair(PID::ELECTRON);
PromptFinalState el_bare(el_id);
Cut cuts = (Cuts::abseta < 2.47) && ( (Cuts::abseta <= 1.37) || (Cuts::abseta >= 1.52) ) && (Cuts::pT > 15*GeV);
LeptonFinder el_dressed_FS(el_bare, photon_id, 0.1, cuts);
declare(el_dressed_FS,"EL_DRESSED_FS");
// Project dressed muons with pT > 15 GeV and |eta| < 2.5
IdentifiedFinalState mu_id(FS);
mu_id.acceptIdPair(PID::MUON);
PromptFinalState mu_bare(mu_id);
LeptonFinder mu_dressed_FS(mu_bare, photon_id, 0.1, Cuts::abseta < 2.5 && Cuts::pT > 15*GeV);
declare(mu_dressed_FS,"MU_DRESSED_FS");
// get MET from generic invisibles
VetoedFinalState inv_fs(FS);
inv_fs.addVetoOnThisFinalState(VisibleFinalState(FS));
declare(inv_fs, "InvisibleFS");
// Project jets
FastJets jets(FS, JetAlg::ANTIKT, 0.4);
jets.useInvisibles(JetInvisibles::NONE);
jets.useMuons(JetMuons::NONE);
declare(jets, "jets");
// Book histograms
book(_h_Njets , 2,1,1);
book(_h_PtllMET , 3,1,1);
book(_h_Yll , 4,1,1);
book(_h_PtLead , 5,1,1);
book(_h_Njets_norm , 6,1,1);
book(_h_PtllMET_norm , 7,1,1);
book(_h_Yll_norm , 8,1,1);
book(_h_PtLead_norm , 9,1,1);
book(_h_JetVeto , 10, 1, 1);
//histos for jetveto
std::vector<double> ptlead25_bins = { 0., 25., 300. };
std::vector<double> ptlead40_bins = { 0., 40., 300. };
book(_h_pTj1_sel25 , "pTj1_sel25", ptlead25_bins);
book(_h_pTj1_sel40 , "pTj1_sel40", ptlead40_bins);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// Get final state particles
const FinalState& ifs = apply<FinalState>(event, "InvisibleFS");
const DressedLeptons& good_mu = apply<LeptonFinder>(event, "MU_DRESSED_FS").dressedLeptons();
const DressedLeptons& el_dressed = apply<LeptonFinder>(event, "EL_DRESSED_FS").dressedLeptons();
const Jets& jets = apply<FastJets>(event, "jets").jetsByPt(Cuts::pT>25*GeV && Cuts::abseta < 4.5);
//find good electrons
DressedLeptons good_el;
for (const DressedLepton& el : el_dressed){
bool keep = true;
for (const DressedLepton& mu : good_mu) {
keep &= deltaR(el, mu) >= 0.1;
}
if (keep) good_el += el;
}
// select only emu events
if ((good_el.size() != 1) || good_mu.size() != 1) vetoEvent;
//built dilepton
FourMomentum dilep = good_el[0].momentum() + good_mu[0].momentum();
double Mll = dilep.mass();
double Yll = dilep.rapidity();
double DPhill = fabs(deltaPhi(good_el[0], good_mu[0]));
double pTl1 = (good_el[0].pT() > good_mu[0].pT())? good_el[0].pT() : good_mu[0].pT();
//get MET
FourMomentum met;
for (const Particle& p : ifs.particles()) met += p.momentum();
// do a few cuts before looking at jets
if (pTl1 <= 22. || DPhill >= 1.8 || met.pT() <= 20.) vetoEvent;
if (Mll <= 10. || Mll >= 55.) vetoEvent;
Jets jets_selected;
for (const Jet &j : jets) {
if( j.abseta() > 2.4 && j.pT()<=30*GeV ) continue;
bool keep = true;
for(DressedLepton el : good_el) {
keep &= deltaR(j, el) >= 0.3;
}
if (keep) jets_selected += j;
}
double PtllMET = (met + good_el[0].momentum() + good_mu[0].momentum()).pT();
double Njets = jets_selected.size() > 2 ? 2 : jets_selected.size();
double pTj1 = jets_selected.size()? jets_selected[0].pT() : 0.1;
// Fill histograms
_h_Njets->fill(Njets);
_h_PtllMET->fill(PtllMET);
_h_Yll->fill(fabs(Yll));
_h_PtLead->fill(pTj1);
_h_Njets_norm->fill(Njets);
_h_PtllMET_norm->fill(PtllMET);
_h_Yll_norm->fill(fabs(Yll));
_h_PtLead_norm->fill(pTj1);
_h_pTj1_sel25->fill(pTj1);
_h_pTj1_sel40->fill(pTj1);
}
/// Normalise histograms etc., after the run
void finalize() {
const double xs = crossSectionPerEvent()/femtobarn;
/// @todo Normalise, scale and otherwise manipulate histograms here
scale(_h_Njets, xs);
scale(_h_PtllMET, xs);
scale(_h_Yll, xs);
scale(_h_PtLead, xs);
normalize(_h_Njets_norm);
normalize(_h_PtllMET_norm);
normalize(_h_Yll_norm);
normalize(_h_PtLead_norm);
scale(_h_pTj1_sel25, xs);
scale(_h_pTj1_sel40, xs);
normalize(_h_pTj1_sel25);
normalize(_h_pTj1_sel40);
// fill jet veto efficiency histogram
_h_JetVeto->bin(1).set(_h_pTj1_sel25->bin(1).sumW(), _h_pTj1_sel25->bin(1).errW());
_h_JetVeto->bin(2).set(_h_PtLead_norm->bin(1).sumW(), _h_PtLead_norm->bin(1).errW());
_h_JetVeto->bin(3).set(_h_pTj1_sel40->bin(1).sumW(), _h_pTj1_sel25->bin(1).errW());
scale(_h_PtLead_norm , 1000.); // curveball unit change in HepData, just for this one
scale(_h_PtllMET_norm, 1000.); // curveball unit change in HepData, and this one
}
private:
/// @name Histograms
/// @{
Histo1DPtr _h_Njets;
Histo1DPtr _h_PtllMET;
Histo1DPtr _h_Yll;
Histo1DPtr _h_PtLead;
Histo1DPtr _h_Njets_norm;
Histo1DPtr _h_PtllMET_norm;
Histo1DPtr _h_Yll_norm;
Histo1DPtr _h_PtLead_norm;
Estimate1DPtr _h_JetVeto;
Histo1DPtr _h_pTj1_sel25;
Histo1DPtr _h_pTj1_sel40;
};
RIVET_DECLARE_PLUGIN(ATLAS_2016_I1444991);
}