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ATLAS_2014_I1310835.cc
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ATLAS_2014_I1310835.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/PromptFinalState.hh"
#include "Rivet/Projections/DressedLeptons.hh"
namespace Rivet {
/// @brief H(125)->ZZ->4l at 8 TeV
class ATLAS_2014_I1310835 : public Analysis {
public:
/// Default constructor
DEFAULT_RIVET_ANALYSIS_CTOR(ATLAS_2014_I1310835);
void init() {
const FinalState fs(Cuts::abseta < 5.0);
PromptFinalState photons(Cuts::abspid == PID::PHOTON);
PromptFinalState bare_el(Cuts::abspid == PID::ELECTRON);
PromptFinalState bare_mu(Cuts::abspid == PID::MUON);
// Selection: lepton selection
Cut etaranges_el = Cuts::abseta < 2.47 && Cuts::pT > 7*GeV;
DressedLeptons electron_sel4l(photons, bare_el, 0.1, etaranges_el, false);
addProjection(electron_sel4l, "electrons");
Cut etaranges_mu = Cuts::abseta < 2.7 && Cuts::pT > 6*GeV;
DressedLeptons muon_sel4l(photons, bare_mu, 0.1, etaranges_mu, false);
addProjection(muon_sel4l, "muons");
FastJets jetpro(fs, FastJets::ANTIKT, 0.4, JetAlg::NO_MUONS, JetAlg::NO_INVISIBLES);
addProjection(jetpro, "jet");
// Book histos
_h_pt = bookHisto1D(1, 1, 1);
_h_rapidity = bookHisto1D(2, 1, 1);
_h_m34 = bookHisto1D(3, 1, 1);
_h_costheta = bookHisto1D(4, 1, 1);
_h_njets = bookHisto1D(5, 1, 1);
_h_leadingjetpt = bookHisto1D(6, 1, 1);
}
/// Do the analysis
void analyze(const Event& e) {
const double weight = e.weight();
////////////////////////////////////////////////////////////////////
// preselection of leptons for ZZ-> llll final state
////////////////////////////////////////////////////////////////////
const vector<DressedLepton>& mu_sel4l = applyProjection<DressedLeptons>(e, "muons").dressedLeptons();
const vector<DressedLepton>& el_sel4l = applyProjection<DressedLeptons>(e, "electrons").dressedLeptons();
vector<DressedLepton> leptonsFS_sel4l;
leptonsFS_sel4l.insert( leptonsFS_sel4l.end(), mu_sel4l.begin(), mu_sel4l.end() );
leptonsFS_sel4l.insert( leptonsFS_sel4l.end(), el_sel4l.begin(), el_sel4l.end() );
/////////////////////////////////////////////////////////////////////////////
/// H->ZZ->4l pairing
/////////////////////////////////////////////////////////////////////////////
size_t el_p = 0;
size_t el_n = 0;
size_t mu_p = 0;
size_t mu_n = 0;
for (const Particle& l : leptonsFS_sel4l) {
if (l.abspid() == PID::ELECTRON) {
if (l.pid() < 0) ++el_n;
if (l.pid() > 0) ++el_p;
}
else if (l.abspid() == PID::MUON) {
if (l.pid() < 0) ++mu_n;
if (l.pid() > 0) ++mu_p;
}
}
bool pass_sfos = ( (el_p >=2 && el_n >=2) || (mu_p >=2 && mu_n >=2) || (el_p >=1 && el_n >=1 && mu_p >=1 && mu_n >=1) );
if (!pass_sfos) vetoEvent;
Zstate Z1, Z2, Zcand;
size_t n_parts = leptonsFS_sel4l.size();
size_t l1_index = 0;
size_t l2_index = 0;
// determine Z1 first
double min_mass_diff = -1;
for (size_t i = 0; i < n_parts; ++i) {
for (size_t j = 0; j < n_parts; ++j) {
if (i >= j) continue;
if (leptonsFS_sel4l[i].pid() != -1*leptonsFS_sel4l[j].pid()) continue; //only pair SFOS leptons
Zcand = Zstate( ParticlePair(leptonsFS_sel4l[i], leptonsFS_sel4l[j]) );
double mass_diff = fabs( Zcand.mom().mass() - 91.1876 );
if (min_mass_diff == -1 || mass_diff < min_mass_diff) {
min_mass_diff = mass_diff;
Z1 = Zcand;
l1_index = i;
l2_index = j;
}
}
}
//determine Z2 second
min_mass_diff = -1;
for (size_t i = 0; i < n_parts; ++i) {
if (i == l1_index || i == l2_index) continue;
for (size_t j = 0; j < n_parts; ++j) {
if (j == l1_index || j == l2_index || i >= j) continue;
if (leptonsFS_sel4l[i].pid() != -1*leptonsFS_sel4l[j].pid()) continue; // only pair SFOS leptons
Zcand = Zstate( ParticlePair(leptonsFS_sel4l[i], leptonsFS_sel4l[j]) );
double mass_diff = fabs( Zcand.mom().mass() - 91.1876 );
if (min_mass_diff == -1 || mass_diff < min_mass_diff) {
min_mass_diff = mass_diff;
Z2 = Zcand;
}
}
}
Particles leptons_sel4l;
leptons_sel4l.push_back(Z1.first);
leptons_sel4l.push_back(Z1.second);
leptons_sel4l.push_back(Z2.first);
leptons_sel4l.push_back(Z2.second);
////////////////////////////////////////////////////////////////////////////
// Kinematic Requirements
///////////////////////////////////////////////////////////////////////////
//leading lepton pT requirement
std::vector<double> lepton_pt;
for (const Particle& i : leptons_sel4l) lepton_pt.push_back(i.pT() / GeV);
std::sort(lepton_pt.begin(), lepton_pt.end(), [](const double pT1, const double pT2) { return pT1 > pT2; });
if (!(lepton_pt[0] > 20*GeV && lepton_pt[1] > 15*GeV && lepton_pt[2] > 10*GeV)) vetoEvent;
//invariant mass requirements
if (!(inRange(Z1.mom().mass(), 50*GeV, 106*GeV) && inRange(Z2.mom().mass(), 12*GeV, 115*GeV))) vetoEvent;
//lepton separation requirements
for (unsigned int i = 0; i < 4; ++i) {
for (unsigned int j = 0; j < 4; ++j) {
if (i >= j) continue;
double dR = deltaR(leptons_sel4l[i], leptons_sel4l[j]);
bool sameflavor = leptons_sel4l[i].abspid() == leptons_sel4l[j].abspid();
if ( sameflavor && dR < 0.1) vetoEvent;
if (!sameflavor && dR < 0.2) vetoEvent;
}
}
// J/Psi veto requirement
for (unsigned int i = 0; i < 4; ++i) {
for (unsigned int j = 0; j < 4; ++j) {
if (i >= j) continue;
if ( leptons_sel4l[i].pid() != -1*leptons_sel4l[j].pid() ) continue;
if ((leptons_sel4l[i].momentum() + leptons_sel4l[j].momentum()).mass() <= 5*GeV) vetoEvent;
}
}
// 4-lepton invariant mass requirement
double m4l = (Z1.mom() + Z2.mom()).mass();
if (!(inRange(m4l, 118*GeV, 129*GeV))) vetoEvent;
////////////////////////////////////////////////////////////////////////////
// Higgs observables
///////////////////////////////////////////////////////////////////////////
FourMomentum Higgs = Z1.mom() + Z2.mom();
double H4l_pt = Higgs.pt()/GeV;
double H4l_rapidity = Higgs.absrap();
LorentzTransform HRF_boost;
//HRF_boost.mkFrameTransformFromBeta(Higgs.boostVector());
HRF_boost.setBetaVec(- Higgs.boostVector());
FourMomentum Z1_in_HRF = HRF_boost.transform( Z1.mom() );
double H4l_costheta = fabs(cos( Z1_in_HRF.theta()));
double H4l_m34 = Z2.mom().mass()/GeV;
////////////////////////////////////////////////////////////////////////////
// Jet observables
///////////////////////////////////////////////////////////////////////////
Jets jets;
for (const Jet& jet : applyProjection<FastJets>(e, "jet").jetsByPt(Cuts::pT > 30*GeV && Cuts::absrap < 4.4)) {
bool overlaps = false;
for (const Particle& lep : leptonsFS_sel4l) {
if (lep.abspid() != PID::ELECTRON) continue;
const double dR = deltaR(lep, jet);
if (dR < 0.2) { overlaps = true; break; }
}
if (!overlaps) jets += jet;
}
size_t n_jets = jets.size();
if (n_jets > 3) n_jets = 3;
std::vector<double> jet_pt;
for (const Jet& i : jets) jet_pt.push_back(i.pT()/GeV);
double leading_jet_pt = n_jets? jet_pt[0] : 0.;
////////////////////////////////////////////////////////////////////////////
// End of H->ZZ->llll selection: now fill histograms
////////////////////////////////////////////////////////////////////////////
_h_pt->fill(H4l_pt, weight);
_h_rapidity->fill(H4l_rapidity, weight);
_h_costheta->fill(H4l_costheta, weight);
_h_m34->fill(H4l_m34, weight);
_h_njets->fill(n_jets + 1, weight);
_h_leadingjetpt->fill(leading_jet_pt, weight);
}
/// Generic Z candidate
struct Zstate : public ParticlePair {
Zstate() { }
Zstate(ParticlePair _particlepair) : ParticlePair(_particlepair) { }
FourMomentum mom() const { return first.momentum() + second.momentum(); }
operator FourMomentum() const { return mom(); }
};
/// Finalize
void finalize() {
const double norm = crossSection()/sumOfWeights()/femtobarn;
std::cout << "xsec: " << crossSection() << std::endl;
std::cout << "sumw: " << sumOfWeights() << std::endl;
std::cout << "femb: " << femtobarn << std::endl;
std::cout << "norm: " << norm << std::endl;
scale(_h_pt, norm);
scale(_h_rapidity, norm);
scale(_h_costheta, norm);
scale(_h_m34, norm);
scale(_h_njets, norm);
scale(_h_leadingjetpt, norm);
}
private:
Histo1DPtr _h_pt, _h_rapidity, _h_costheta;
Histo1DPtr _h_m34, _h_njets, _h_leadingjetpt;
};
// The hook for the plugin system
DECLARE_RIVET_PLUGIN(ATLAS_2014_I1310835);
}

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