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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/InvisibleFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/DressedLeptons.hh"
#include "Rivet/Projections/MissingMomentum.hh"
#include "Rivet/Projections/PromptFinalState.hh"
#include "Rivet/Projections/PartonicTops.hh"
#include "Rivet/Projections/VetoedFinalState.hh"
#include "Rivet/Tools/MendelMin.hh"
#include "fastjet/tools/Filter.hh"
namespace Rivet {
/// @brief Energy asymmetry in ttj at 13 TeV
class ATLAS_2021_I1941095 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2021_I1941095);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Declare projections
// Photons
PromptFinalState promptphotons(Cuts::abspid == PID::PHOTON, false);
// Electrons
PromptFinalState bare_el(Cuts::abspid == PID::ELECTRON, true); // true = use electrons from prompt tau decays
DressedLeptons all_dressed_el(promptphotons, bare_el, 0.1, Cuts::abseta < 2.5, true);
DressedLeptons electrons(promptphotons, bare_el, 0.1, Cuts::abseta < 2.5 && Cuts::pT > 25*GeV, true);
declare(electrons,"electrons");
// Muons
PromptFinalState bare_mu(Cuts::abspid == PID::MUON, true); // true = use muons from prompt tau decays
DressedLeptons all_dressed_mu(promptphotons, bare_mu, 0.1, Cuts::abseta < 2.5, true);
DressedLeptons muons(promptphotons,bare_mu, 0.1, Cuts::abseta <2.5 && Cuts::pT > 25*GeV, true);
declare(muons,"muons");
// AntiKt4TruthWZJets as AntiKt4TruthWZJets, but w/o photons from hadrons in dressing
const InvisibleFinalState invisibles(true, true);
VetoedFinalState vfs(FinalState(Cuts::abseta < 5.0)); // changed from 4.5 to 5.0
vfs.addVetoOnThisFinalState(all_dressed_el);
vfs.addVetoOnThisFinalState(all_dressed_mu);
vfs.addVetoOnThisFinalState(invisibles); // new
FastJets jets(vfs, FastJets::ANTIKT, 0.4, JetAlg::Muons::ALL, JetAlg::Invisibles::ALL); // changed invisible from DECAY to ALL
declare(jets,"jets");
// AntiKt10TruthTrimmedPtFrac5SmallR20Jets
FinalState fs(Cuts::abseta < 5.0);
FastJets fjets(fs, FastJets::ANTIKT, 1.0, JetAlg::Muons::NONE, JetAlg::Invisibles::NONE);
_trimmer = fastjet::Filter(fastjet::JetDefinition(fastjet::kt_algorithm, 0.2), fastjet::SelectorPtFractionMin(0.05));
declare(fjets,"fjets");
// Missing momentum
declare(MissingMomentum(), "MissingMomentum");
// Parton level top quarks after FSR
// options are: decaymode, emu_from_prompt_tau, include_hadronic_taus
declare(PartonicTops(PartonicTops::DecayMode::E_MU, true, false), "PartonicTops_EMU");
declare(PartonicTops(PartonicTops::DecayMode::E_MU, false, false), "PartonicTops_EMU_notau");
declare(PartonicTops(PartonicTops::DecayMode::HADRONIC, false, true), "PartonicTops_HADRONIC");
declare(PartonicTops(PartonicTops::DecayMode::HADRONIC, false, false), "PartonicTops_HADRONIC_notau");
// Book histograms
const Scatter2D& ref_asymm = refData(1, 1, 1);
book(_h["pos"], "_thetaj_opt_depos", ref_asymm);
book(_h["neg"], "_thetaj_opt_deneg", ref_asymm);
book(_asymm, 1, 1, 1, true);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// Parton-level top quarks // after FSR
const Particles partonicTops_EMU = apply<ParticleFinder>(event, "PartonicTops_EMU").particlesByPt();
const Particles partonicTops_EMU_notau = apply<ParticleFinder>(event, "PartonicTops_EMU_notau").particlesByPt();
const Particles partonicTops_HADRONIC = apply<ParticleFinder>(event, "PartonicTops_HADRONIC").particlesByPt();
const Particles partonicTops_HADRONIC_notau = apply<ParticleFinder>(event, "PartonicTops_HADRONIC_notau").particlesByPt();
// Filter semi-leptonic (e,mu,tau) events: Veto dileptonic/nonleptonic events and events with 2 taus
int nLeptons = partonicTops_EMU.size() + partonicTops_HADRONIC.size() - partonicTops_HADRONIC_notau.size();
if (nLeptons != 1) vetoEvent;
// Get the selected objects, using the projections.
vector<DressedLepton> electrons = apply<DressedLeptons>(event, "electrons").dressedLeptons();
vector<DressedLepton> muons = apply<DressedLeptons>(event, "muons").dressedLeptons();
const Jets& jets = apply<FastJets>(event, "jets").jetsByPt(Cuts::pT > 25*GeV && Cuts::abseta < 2.5);
const Jets& fjets = apply<FastJets>(event, "fjets").jetsByPt(Cuts::pT > 200*GeV && Cuts::abseta < 2.0);
PseudoJets ljets;
for (const Jet& fjet : fjets) { ljets += _trimmer(fjet); }
sort(ljets.begin(), ljets.end(), [](PseudoJet const &l, PseudoJet const &r) { return l.pt() > r.pt(); });
const FourMomentum& met = apply<MissingMomentum>(event, "MissingMomentum").missingMomentum();
// Overlap removal
for (const Jet& jet : jets) {
ifilter_discard(electrons, deltaRLess(jet, 0.4, RAPIDITY));
ifilter_discard(muons, deltaRLess(jet, 0.4, RAPIDITY));
}
// Reconstruct event
// Lepton l
size_t n_el_25 = 0, n_el_27 = 0;
for (const DressedLepton& electron : electrons ) {
if (electron.pT() >= 25*GeV) ++n_el_25;
if (electron.pT() >= 27*GeV) ++n_el_27;
}
size_t n_mu_25 = 0, n_mu_27 = 0;
for (const DressedLepton& muon : muons ) {
if (muon.pT() >= 25*GeV) ++n_mu_25;
if (muon.pT() >= 27*GeV) ++n_mu_27;
}
if ((n_el_25 + n_mu_25 != 1) || (n_el_27 + n_mu_27 != 1)) vetoEvent;
DressedLepton lepton = (n_el_27 == 1)? electrons[0] : muons[0];
FourMomentum l = lepton.mom();
int lep_charge = lepton.charge();
// Neutrino nu
FourMomentum nu = getNeutrino(l, met);
// Hadronic top candidate jh
int jh_idx = -1;
for (size_t ijet = 0; ijet < ljets.size(); ++ijet) {
Jet ljet = Jet(ljets[ijet]);
if (ljet.pT() < 350*GeV) continue;
if (ljet.abseta() > 2.0) continue;
if (ljet.mass() < 140*GeV) continue;
if (deltaPhi(ljet,l) < 1.0) continue;
bool btagged = false;
for (const Jet& jet : jets) {
if ( jet.bTagged(Cuts::pT > 5*GeV) ) {
if ( deltaR(ljet, jet) < 1.0 ) {
btagged = true;
break;
}
}
}
if (btagged) {
jh_idx = ijet;
break;
}
}
if ( jh_idx == -1 ) vetoEvent;
FourMomentum jh = Jet(ljets[jh_idx]).mom();
// Leptonic top b-jet candidate jl
int jl_idx = -1;
for (size_t ijet = 0; ijet < jets.size(); ++ijet) {
if ( !jets[ijet].bTagged(Cuts::pT > 5*GeV) ) continue;
if ( deltaR(jets[ijet], l) > 2.0 ) continue;
if ( deltaR(jets[ijet], jh) < 1.5 ) continue;
jl_idx = ijet;
break;
}
if ( jl_idx == -1) {
for (size_t ijet = 0; ijet < jets.size(); ++ijet) {
if ( deltaR(jets[ijet], l) > 2.0 ) continue;
if ( deltaR(jets[ijet], jh) < 1.5 ) continue;
jl_idx = ijet;
break;
}
}
if ( jl_idx == -1 ) vetoEvent;
FourMomentum jl = Jet(jets[jl_idx]).mom();
// b-tagging
size_t n_btagged = 0;
size_t n_btagged_matched = 1; // Large-jet jh is b-tagged
for (const Jet& jet : jets ) {
if (jet.bTagged(Cuts::pT > 5*GeV)) ++n_btagged;
}
if ( jets[jl_idx].bTagged(Cuts::pT > 5*GeV) ) ++n_btagged_matched;
if ( n_btagged >= 2 && n_btagged_matched < 2 ) vetoEvent;
// Associated jet candidate ja
int ja_idx = -1;
for (int ijet = 0; ijet < int(jets.size()); ++ijet) {
if ( ijet == jl_idx ) continue;
if ( jets[ijet].pT() < 100*GeV ) continue;
if ( deltaR(jets[ijet], jh) < 1.5 ) continue;
if ( deltaR(jets[ijet], l) < 0.4 ) continue;
ja_idx = ijet;
break;
}
if ( ja_idx == -1 ) vetoEvent;
FourMomentum ja = jets[ja_idx].mom();
FourMomentum thad = jh;
FourMomentum tlep = l+nu+jl;
FourMomentum top = lep_charge > 0 ? tlep : thad;
FourMomentum tbar = lep_charge > 0 ? thad : tlep;
FourMomentum ttbar = top + tbar;
FourMomentum ttj = top + tbar + ja;
// Boost into ttj reference frame
FourMomentum ttj_inv( ttj.E(), -ttj.px(), -ttj.py(), -ttj.pz() );
Vector3 boostVector = ttj_inv.betaVec();
LorentzTransform lt_boost;
lt_boost.setBetaVec( boostVector );
FourMomentum top_boosted = lt_boost.transform( top );
FourMomentum tbar_boosted = lt_boost.transform( tbar );
FourMomentum ja_boosted = lt_boost.transform( ja );
// Get observables
const double deltaE = top_boosted.E() - tbar_boosted.E();
const double thetaj_opt = ttj.rapidity() > 0 ? ja_boosted.theta() : pi - ja_boosted.theta();
// Fill auxiliary histograms
_h[deltaE > 0 ? "pos" : "neg"]->fill(thetaj_opt);
}
/// Normalise histograms etc., after the run
void finalize() {
scale(_h, crossSection()/picobarn/sumW());
// Calculate differential energy asymmetry
asymm(_h["pos"], _h["neg"], _asymm);
}
/// @}
private:
fastjet::Filter _trimmer;
// Histograms
map<string, Histo1DPtr> _h;
Scatter2DPtr _asymm;
static double delta2_fcn(const MendelMin::Params& p, const MendelMin::Params& pfix) {
double delta2 = 0;
double alpha = p[0]*6.30-3.15; // Map p[0] in [0,1] to alpha in [-3.15,3.15]
double r = pfix[0];
double dphi = pfix[1];
double l_pt = pfix[2];
double l_m = pfix[3];
double n_px = pfix[4];
double n_py = pfix[5];
r /= sqrt(l_pt * l_pt + l_m * l_m) - l_pt * cos(dphi + alpha);
FourMomentum neut(0.0, n_px, n_py, 0.0); // E, px, py, pz
neut.setE(neut.p());
FourMomentum neut_new( 0.0, r * neut.p() * cos(neut.phi() + alpha), r * neut.p() * sin(neut.phi() + alpha), 0.0 );
neut_new.setE(neut_new.p());
delta2 = pow((neut_new.px() - neut.px()), 2) + pow((neut_new.py() - neut.py()), 2);
return delta2;
}
FourMomentum getNeutrino(const FourMomentum& lepton, const FourMomentum& met) {
const double m_mWpdg = 80.4*GeV;
double pxNu = met.px();
double pyNu = met.py();
double ptNu = met.pt();
double pzNu;
double c1 = pow(m_mWpdg,2) - pow(lepton.mass(),2) + 2 * (lepton.px() * pxNu + lepton.py() * pyNu);
double b1 = 2 * lepton.pz();
double A = 4*pow(lepton.E(),2) - b1*b1;
double B = -2 * c1 * b1;
double C = 4 * pow(lepton.E(), 2) * ptNu * ptNu - c1 * c1;
double discr = B*B - 4*A*C;
double r = 1;
double sol1, sol2;
if (discr > 0){
sol1 = (-B + sqrt(discr)) / (2*A);
sol2 = (-B - sqrt(discr)) / (2*A);
}
else {
// fitAlpha
std::valarray<double> pfix = { (m_mWpdg * m_mWpdg - lepton.mass() * lepton.mass()) / (2 * ptNu), met.phi() - lepton.phi(),
lepton.pt(), lepton.mass(), pxNu, pyNu };
MendelMin mm(delta2_fcn, 1, pfix);
mm.evolve(100);
valarray<double> fittest = mm.fittest();
const double alpha = fittest[0]*6.30-3.15; // map p[0] in [0,1] to alpha in [-3.15,3.15]
const double dphi = met.phi() - lepton.phi();
r = ( pow(m_mWpdg,2) - pow(lepton.mass(),2) );
r /= (2 * ptNu * (sqrt(pow(lepton.pt(),2) + pow(lepton.mass(),2)) - lepton.pt() * cos(dphi + alpha)));
const double old_p = ptNu;
const double old_phi = met.phi();
pxNu = r * old_p * cos(old_phi + alpha);
pyNu = r * old_p * sin(old_phi + alpha);
ptNu = sqrt (pxNu*pxNu + pyNu*pyNu);
c1 = pow(m_mWpdg,2) - pow(lepton.mass(),2) + 2 * (lepton.px() * pxNu + lepton.py() * pyNu);
B = -2 * c1 * b1;
C = 4 * pow(lepton.E(),2) * ptNu * ptNu - c1 * c1;
discr = B*B - 4*A*C;
sol1 = -B / (2*A);
sol2 = -B / (2*A);
}
// useSmallestPz
pzNu = (fabs(sol1) > fabs(sol2)) ? sol2 : sol1;
FourMomentum nu( sqrt(sqr(pxNu) + sqr(pyNu) + sqr(pzNu)), pxNu, pyNu, pzNu);
return nu;
}
};
RIVET_DECLARE_PLUGIN(ATLAS_2021_I1941095);
}
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