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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/VetoedFinalState.hh"
#include "Rivet/Projections/IdentifiedFinalState.hh"
#include "Rivet/Projections/PromptFinalState.hh"
#include "Rivet/Projections/DressedLeptons.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/VisibleFinalState.hh"
namespace Rivet {
class ATLAS_2015_I1404878 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2015_I1404878);
void init() {
// Eta ranges
Cut eta_full = (Cuts::abseta < 4.2) & (Cuts::pT >= 1.0*MeV);
Cut lep_cuts = (Cuts::abseta < 2.5) && (Cuts::pT > 25*GeV);
// All final state particles
FinalState fs(eta_full);
// Get photons to dress leptons
IdentifiedFinalState photons(fs);
photons.acceptIdPair(PID::PHOTON);
// Projection to find the electrons
IdentifiedFinalState el_id(fs);
el_id.acceptIdPair(PID::ELECTRON);
PromptFinalState electrons(el_id);
electrons.acceptTauDecays(true);
declare(electrons, "electrons");
DressedLeptons dressedelectrons(photons, electrons, 0.1, lep_cuts, true);
declare(dressedelectrons, "dressedelectrons");
DressedLeptons ewdressedelectrons(photons, electrons, 0.1, eta_full, true);
declare(ewdressedelectrons, "ewdressedelectrons");
// Projection to find the muons
IdentifiedFinalState mu_id(fs);
mu_id.acceptIdPair(PID::MUON);
PromptFinalState muons(mu_id);
muons.acceptTauDecays(true);
declare(muons, "muons");
DressedLeptons dressedmuons(photons, muons, 0.1, lep_cuts, true);
declare(dressedmuons, "dressedmuons");
DressedLeptons ewdressedmuons(photons, muons, 0.1, eta_full, true);
declare(ewdressedmuons, "ewdressedmuons");
// Projection to find neutrinos
IdentifiedFinalState nu_id;
nu_id.acceptNeutrinos();
PromptFinalState neutrinos(nu_id);
neutrinos.acceptTauDecays(true);
// get MET from generic invisibles
VetoedFinalState inv_fs(fs);
inv_fs.addVetoOnThisFinalState(VisibleFinalState(fs));
declare(inv_fs, "InvisibleFS");
// Jet clustering.
VetoedFinalState vfs;
vfs.addVetoOnThisFinalState(ewdressedelectrons);
vfs.addVetoOnThisFinalState(ewdressedmuons);
vfs.addVetoOnThisFinalState(neutrinos);
FastJets jets(vfs, FastJets::ANTIKT, 0.4, JetAlg::Muons::ALL, JetAlg::Invisibles::DECAY);
declare(jets, "jets");
// Histogram booking
book(_h["massttbar"] , 1, 1, 1);
book(_h["massttbar_norm"] , 2, 1, 1);
book(_h["ptttbar"] , 3, 1, 1);
book(_h["ptttbar_norm"] , 4, 1, 1);
book(_h["absrapttbar"] , 5, 1, 1);
book(_h["absrapttbar_norm"] , 6, 1, 1);
book(_h["ptpseudotophadron"] , 7, 1, 1);
book(_h["ptpseudotophadron_norm"] , 8, 1, 1);
book(_h["absrappseudotophadron"] , 9, 1, 1);
book(_h["absrappseudotophadron_norm"] ,10, 1, 1);
book(_h["absPout"] ,11, 1, 1);
book(_h["absPout_norm"] ,12, 1, 1);
book(_h["dPhittbar"] ,13, 1, 1);
book(_h["dPhittbar_norm"] ,14, 1, 1);
book(_h["HTttbar"] ,15, 1, 1);
book(_h["HTttbar_norm"] ,16, 1, 1);
book(_h["Yboost"] ,17, 1, 1);
book(_h["Yboost_norm"] ,18, 1, 1);
book(_h["chittbar"] ,19, 1, 1);
book(_h["chittbar_norm"] ,20, 1, 1);
book(_h["RWt"] ,21, 1, 1);
book(_h["RWt_norm"] ,22, 1, 1);
}
void analyze(const Event& event) {
// Get the selected objects, using the projections.
vector<DressedLepton> electrons = applyProjection<DressedLeptons>(event, "dressedelectrons").dressedLeptons();
vector<DressedLepton> muons = applyProjection<DressedLeptons>(event, "dressedmuons").dressedLeptons();
const Jets& jets = applyProjection<FastJets>(event, "jets").jetsByPt(Cuts::pT > 25*GeV && Cuts::abseta < 2.5);
const FinalState& ifs = applyProjection<FinalState>(event, "InvisibleFS");
// Calculate MET
FourMomentum met;
for (const Particle& p : ifs.particles()) met += p.momentum();
// Count the number of b-tags
Jets bjets, lightjets;
for (const Jet& jet : jets){
bool b_tagged = jet.bTags(Cuts::pT > 5*GeV).size();
if ( b_tagged && bjets.size() < 2 ) bjets += jet;
else lightjets += jet;
}
bool single_electron = (electrons.size() == 1) && (muons.empty());
bool single_muon = (muons.size() == 1) && (electrons.empty());
DressedLepton* lepton = nullptr;
if (single_electron) lepton = &electrons[0];
else if (single_muon) lepton = &muons[0];
if(!single_electron && !single_muon) vetoEvent;
if (jets.size() < 4 || bjets.size() < 2) vetoEvent;
FourMomentum pbjet1; // Momentum of bjet1
FourMomentum pbjet2; // Momentum of bjet2
if ( deltaR(bjets[0], *lepton) <= deltaR(bjets[1], *lepton) ) {
pbjet1 = bjets[0].momentum();
pbjet2 = bjets[1].momentum();
} else {
pbjet1 = bjets[1].momentum();
pbjet2 = bjets[0].momentum();
}
double bestWmass = 1000.0*TeV;
double mWPDG = 80.399*GeV;
int Wj1index = -1, Wj2index = -1;
for (unsigned int i = 0; i < (lightjets.size() - 1); ++i) {
for (unsigned int j = i + 1; j < lightjets.size(); ++j) {
double wmass = (lightjets[i].momentum() + lightjets[j].momentum()).mass();
if (fabs(wmass - mWPDG) < fabs(bestWmass - mWPDG)) {
bestWmass = wmass;
Wj1index = i;
Wj2index = j;
}
}
}
// Compute hadronic W boson
FourMomentum pWhadron = lightjets[Wj1index].momentum() + lightjets[Wj2index].momentum();
double pz = _computeneutrinoz(lepton->momentum(), met);
FourMomentum ppseudoneutrino( sqrt(sqr(met.px()) + sqr(met.py()) + sqr(pz)), met.px(), met.py(), pz);
// Compute leptonic, hadronic, combined pseudo-top
FourMomentum ppseudotoplepton = lepton->momentum() + ppseudoneutrino + pbjet1;
FourMomentum ppseudotophadron = pbjet2 + pWhadron;
FourMomentum pttbar = ppseudotoplepton + ppseudotophadron;
Vector3 z_versor(0,0,1);
Vector3 vpseudotophadron = ppseudotophadron.vector3();
Vector3 vpseudotoplepton = ppseudotoplepton.vector3();
// Observables
double ystar = 0.5 * deltaRap(ppseudotophadron, ppseudotoplepton);
double chi_ttbar = exp(2 * fabs(ystar));
double deltaPhi_ttbar = deltaPhi(ppseudotoplepton,ppseudotophadron);
double HT_ttbar = ppseudotophadron.pt() + ppseudotoplepton.pt();
double Yboost = 0.5 * fabs(ppseudotophadron.rapidity() + ppseudotoplepton.rapidity());
double R_Wt = pWhadron.pt() / ppseudotophadron.pt();
double absPout = fabs(vpseudotophadron.dot((vpseudotoplepton.cross(z_versor))/(vpseudotoplepton.cross(z_versor).mod())));
// absolute cross sections
_h["ptpseudotophadron"]->fill( ppseudotophadron.pt()); //pT of pseudo top hadron
_h["ptttbar"]->fill( pttbar.pt()); //fill pT of ttbar in combined channel
_h["absrappseudotophadron"]->fill(ppseudotophadron.absrap());
_h["absrapttbar"]->fill( pttbar.absrap());
_h["massttbar"]->fill( pttbar.mass());
_h["absPout"]->fill( absPout);
_h["chittbar"]->fill( chi_ttbar);
_h["dPhittbar"]->fill( deltaPhi_ttbar);
_h["HTttbar"]->fill( HT_ttbar);
_h["Yboost"]->fill( Yboost);
_h["RWt"]->fill( R_Wt);
// normalised cross sections
_h["ptpseudotophadron_norm"]->fill( ppseudotophadron.pt()); //pT of pseudo top hadron
_h["ptttbar_norm"]->fill( pttbar.pt()); //fill pT of ttbar in combined channel
_h["absrappseudotophadron_norm"]->fill(ppseudotophadron.absrap());
_h["absrapttbar_norm"]->fill( pttbar.absrap());
_h["massttbar_norm"]->fill( pttbar.mass());
_h["absPout_norm"]->fill( absPout);
_h["chittbar_norm"]->fill( chi_ttbar);
_h["dPhittbar_norm"]->fill( deltaPhi_ttbar);
_h["HTttbar_norm"]->fill( HT_ttbar);
_h["Yboost_norm"]->fill( Yboost);
_h["RWt_norm"]->fill( R_Wt);
}
void finalize() {
// Normalize to cross-section
const double sf = crossSection() / sumOfWeights();
for (auto& k_h : _h) {
scale(k_h.second, sf);
if (k_h.first.find("_norm") != string::npos) normalize(k_h.second);
}
}
private:
// Compute z component of neutrino momentum given lepton and met
double _computeneutrinoz(const FourMomentum& lepton, FourMomentum& met) const {
double m_W = 80.399; // in GeV, given in the paper
double k = (( sqr( m_W ) - sqr( lepton.mass() ) ) / 2 ) + (lepton.px() * met.px() + lepton.py() * met.py());
double a = sqr ( lepton.E() )- sqr ( lepton.pz() );
double b = -2*k*lepton.pz();
double c = sqr( lepton.E() ) * sqr( met.pT() ) - sqr( k );
double discriminant = sqr(b) - 4 * a * c;
double quad[2] = { (- b - sqrt(discriminant)) / (2 * a), (- b + sqrt(discriminant)) / (2 * a) }; //two possible quadratic solns
double pzneutrino;
if (discriminant < 0) { // if the discriminant is negative:
pzneutrino = - b / (2 * a);
} else { // if the discriminant is positive, take the soln with smallest absolute value
pzneutrino = (fabs(quad[0]) < fabs(quad[1])) ? quad[0] : quad[1];
}
return pzneutrino;
}
/// @todo Replace with central version
double _mT(const FourMomentum &l, FourMomentum &nu) const {
return sqrt( 2 * l.pT() * nu.pT() * (1 - cos(deltaPhi(l, nu))) );
}
/// @name Objects that are used by the event selection decisions
map<string, Histo1DPtr> _h;
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(ATLAS_2015_I1404878);
}
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