Rivet analyses
4 or more lepton plus missing transverse energy SUSY search
Experiment: ATLAS (LHC)
Inspire ID: 1229998
Status: PRELIMINARY
Authors: - Peter Richardson
References: - Expt page: ATLAS-CONF-2012-153
Beams: p+ p+
Beam energies: (4000.0, 4000.0)GeV
Run details: - BSM signal events at 8000 GeV.
Search for SUSY using events with 4 or more leptons in association with missing transverse energy in proton-proton collisions at a centre-of-mass energy of 8 TeV. The data sample has a total integrated luminosity of 13.0 fb−1. There is no reference data and in addition to the control plots from the paper the number of events in the two signal regions, correctly normalized to an integrated luminosity 13.0 fb−1, are calculated.
Source
code:ATLAS_2012_CONF_2012_153.cc
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/VisibleFinalState.hh"
#include "Rivet/Projections/VetoedFinalState.hh"
#include "Rivet/Projections/IdentifiedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Tools/RivetMT2.hh"
namespace Rivet {
class ATLAS_2012_CONF_2012_153 : public Analysis {
public:
/// @name Constructors etc.
/// @{
/// Constructor
ATLAS_2012_CONF_2012_153()
: Analysis("ATLAS_2012_CONF_2012_153")
{ }
/// @}
public:
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// projection to find the electrons
IdentifiedFinalState elecs(Cuts::abseta < 2.47 && Cuts::pT > 10*GeV);
elecs.acceptIdPair(PID::ELECTRON);
declare(elecs, "elecs");
// projection to find the muons
IdentifiedFinalState muons(Cuts::abseta < 2.4 && Cuts::pT > 10*GeV);
muons.acceptIdPair(PID::MUON);
declare(muons, "muons");
// for pTmiss
declare(VisibleFinalState(Cuts::abseta < 4.9), "vfs");
VetoedFinalState vfs;
vfs.addVetoPairId(PID::MUON);
/// Jet finder
declare(FastJets(vfs, JetAlg::ANTIKT, 0.4), "AntiKtJets04");
// all tracks (to do deltaR with leptons)
declare(ChargedFinalState(Cuts::abseta < 3.0), "cfs");
vector<double> edges_meff;
edges_meff.push_back( 0);
edges_meff.push_back( 150);
edges_meff.push_back( 300);
edges_meff.push_back( 500);
edges_meff.push_back(1000);
edges_meff.push_back(1500);
vector<double> edges_eT;
edges_eT.push_back(0);
edges_eT.push_back(50);
edges_eT.push_back(150);
edges_eT.push_back(300);
edges_eT.push_back(500);
// Book histograms
book(_hist_electrons ,"hist_electrons_before", 11, -0.5,10.5);
book(_hist_muons ,"hist_muons_before" , 11, -0.5,10.5);
book(_hist_leptons ,"hist_leptons_before" , 11, -0.5,10.5);
book(_hist_4leptons ,"hist_4leptons", 1, 0.,1.);
book(_hist_veto ,"hist_veto", 1, 0., 1.);
book(_hist_etmiss ,"hist_etmiss",edges_eT);
book(_hist_meff ,"hist_m_eff",edges_meff);
book(_count_SR1 ,"count_SR1", 1, 0., 1.);
book(_count_SR2 ,"count_SR2", 1, 0., 1.);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// get the jet candidates
Jets cand_jets = apply<FastJets>(event, "AntiKtJets04").jetsByPt(Cuts::pT > 20*GeV && Cuts::abseta < 2.5);
// candidate muons
Particles cand_mu = apply<IdentifiedFinalState>(event, "muons").particlesByPt();
// candidate electrons
// Discard if two electrons are within R=0.1
Particles temp = apply<IdentifiedFinalState>(event, "elecs").particles(cmpMomByE);
vector<bool> vetoed(temp.size(),false);
Particles cand_e;
for (size_t ix = 0; ix < temp.size(); ++ix) {
if (vetoed[ix]) continue;
for (size_t iy = ix+1; iy < temp.size(); ++iy) {
if ( deltaR(temp[ix], temp[iy]) < 0.1 ) vetoed[iy] = true;
}
if (!vetoed[ix]) cand_e.push_back(temp[ix]);
}
// Sort by transverse momentum
isortByPt(cand_e);
// resolve jet/lepton ambiguity
Jets recon_jets;
for ( const Jet& jet : cand_jets ) {
bool away_from_e = true;
for ( const Particle& e : cand_e ) {
if (deltaR(e, jet) <= 0.2) {
away_from_e = false;
break;
}
}
if (away_from_e) recon_jets.push_back( jet );
}
// only keep electrons more than R=0.4 from jets
Particles cand2_e;
for (const Particle& e : cand_e) {
// at least 0.4 from any jets
bool away = true;
for ( const Jet& jet : recon_jets ) {
if ( deltaR(e, jet) < 0.4 ) {
away = false;
break;
}
}
// if isolated keep it
if ( away )
cand2_e.push_back( e );
}
// only keep muons more than R=0.4 from jets
Particles cand2_mu;
for(const Particle & mu : cand_mu ) {
bool away = true;
// at least 0.4 from any jets
for ( const Jet& jet : recon_jets ) {
if ( deltaR(mu, jet) < 0.4 ) {
away = false;
break;
}
}
if (away) cand2_mu.push_back( mu );
}
// electron and muon more than 0.1 apart
Particles cand3_e;
for ( const Particle & e : cand2_e ) {
bool away = true;
for( const Particle & mu : cand2_mu ) {
if( deltaR(e, mu) < 0.1) {
away = false;
break;
}
}
if (away) cand3_e.push_back(e);
}
Particles cand3_mu;
for( const Particle & mu : cand2_mu ) {
bool away = true;
for ( const Particle & e : cand2_e ) {
if( deltaR(e, mu) < 0.1) {
away = false;
break;
}
}
if (away) cand3_mu.push_back(mu);
}
// pTmiss
Particles vfs_particles =
apply<VisibleFinalState>(event, "vfs").particles();
FourMomentum pTmiss;
for ( const Particle & p : vfs_particles ) {
pTmiss -= p.momentum();
}
double eTmiss = pTmiss.pT();
// apply electron isolation
Particles chg_tracks =
apply<ChargedFinalState>(event, "cfs").particles();
Particles cand4_e;
for (const Particle& e : cand3_e) {
// charge isolation
double pTinCone = -e.pT();
for (const Particle& track : chg_tracks) {
if (track.pT() > 0.4*GeV && deltaR(e, track) <= 0.3 )
pTinCone += track.pT();
}
if (pTinCone/e.pT() > 0.16) continue;
// all particles isolation
pTinCone = -e.pT();
for (const Particle& p : vfs_particles) {
if (p.abspid() != PID::MUON && deltaR(e, p) <= 0.3 )
pTinCone += p.pT();
}
if (pTinCone/e.pT() < 0.18) cand4_e.push_back(e);
}
// apply muon isolation
Particles cand4_mu;
for ( const Particle & mu : cand3_mu ) {
double pTinCone = -mu.perp();
for ( const Particle & track : chg_tracks ) {
if (track.pT() > 1*GeV && deltaR(mu, track) <= 0.3)
pTinCone += track.pT();
}
if (pTinCone/mu.pT() < 0.12) cand4_mu.push_back(mu);
}
// same SOSF pairs m>12.
Particles recon_e;
for(const Particle& e : cand4_e) {
bool veto = false;
for(const Particle& e2 : cand4_e) {
if (e.pid()*e2.pid() < 0 && (e.momentum()+e2.momentum()).mass() < 12*GeV) {
veto = true;
break;
}
}
if (!veto) recon_e.push_back(e);
}
Particles recon_mu;
for(const Particle& mu : cand4_mu) {
bool veto = false;
for(const Particle& mu2 : cand4_mu) {
if (mu.pid()*mu2.pid() < 0 && (mu.momentum()+mu2.momentum()).mass() < 12*GeV) {
veto = true;
break;
}
}
if (!veto) recon_mu.push_back(mu);
}
// now only use recon_jets, recon_mu, recon_e
_hist_electrons->fill(recon_e.size());
_hist_muons->fill(recon_mu.size());
_hist_leptons->fill(recon_mu.size() + recon_e.size());
if (recon_mu.size() + recon_e.size() > 3) {
_hist_4leptons->fill(0.5);
}
// reject events with less than 4 electrons and muons
if (recon_mu.size() + recon_e.size() < 4) {
MSG_DEBUG("To few charged leptons left after selection");
vetoEvent;
}
// or two lepton trigger
bool passDouble =
(recon_mu.size()>=2 && ( (recon_mu[1].pT()>14*GeV) ||
(recon_mu[0].pT()>18*GeV && recon_mu[1].perp() > 10*GeV) )) ||
(recon_e.size() >=2 && ( (recon_e [1].pT()>14*GeV) ||
(recon_e [0].pT()>25*GeV && recon_e [1].perp() > 10*GeV) )) ||
(!recon_e.empty() && !recon_mu.empty() &&
( (recon_e[0].pT() > 14*GeV && recon_mu[0].pT() > 10*GeV)||
(recon_e[0].pT() > 10*GeV && recon_mu[0].pT() > 18*GeV) ));
// must pass a trigger
if (!passDouble ) {
MSG_DEBUG("Hardest lepton fails trigger");
_hist_veto->fill(0.5);
vetoEvent;
}
// calculate meff
double meff = eTmiss;
for ( const Particle & e : recon_e ) meff += e.perp();
for ( const Particle & mu : recon_mu ) meff += mu.perp();
for ( const Jet & jet : recon_jets ) {
const double pT = jet.pT();
if (pT > 40*GeV) meff += pT;
}
// 2/3 leptons --> find 1 SFOS pair in range and veto event
// 4+ leptons --> find 2 SFOS pairs and in range veto event
for (size_t ix = 0; ix < recon_e.size(); ++ix) {
for (size_t iy = ix+1; iy < recon_e.size(); ++iy) {
if (recon_e[ix].pid()*recon_e[iy].pid() > 0) continue;
const FourMomentum ppair = recon_e[ix].momentum() + recon_e[iy].momentum();
if (inRange(ppair.mass(), 81.2*GeV, 101.2*GeV)) vetoEvent;
// check triplets with electron
for (size_t iz = 0; iz < recon_e.size(); ++iz) {
if (iz == ix || iz == iy) continue;
if (inRange((ppair+recon_e[iz].momentum()).mass(), 81.2*GeV, 101.2*GeV)) vetoEvent;
}
// check triplets with muon
for (size_t iz = 0; iz < recon_mu.size(); ++iz) {
if (inRange((ppair+recon_mu[iz].momentum()).mass(), 81.2*GeV, 101.2*GeV)) vetoEvent;
}
// check quadruplets with electrons
for (size_t iz = 0; iz < recon_e.size(); ++iz) {
for (size_t iw = iz+1; iw < recon_e.size(); ++iw) {
if (iz==ix || iz==iy || iw==ix || iw==iy) continue;
if (recon_e[iz].pid()*recon_e[iw].pid() > 0) continue;
if (inRange((ppair+recon_e[iz].momentum()+recon_e[iw].momentum()).mass(), 81.2*GeV, 101.2*GeV)) vetoEvent;
}
}
// check quadruplets with muons
for (size_t iz = 0; iz < recon_mu.size(); ++iz) {
for (size_t iw = iz+1; iw < recon_mu.size(); ++iw) {
if (recon_mu[iz].pid()*recon_mu[iw].pid() > 0) continue;
if (inRange((ppair+recon_mu[iz].momentum()+recon_mu[iw].momentum()).mass(), 81.2*GeV, 101.2*GeV)) vetoEvent;
}
}
}
}
// Muon pairs
for (size_t ix = 0; ix < recon_mu.size(); ++ix) {
for (size_t iy = ix+1; iy < recon_mu.size(); ++iy) {
if (recon_mu[ix].pid()*recon_mu[iy].pid()>0) continue;
const FourMomentum ppair = recon_mu[ix].momentum()+recon_mu[iy].momentum();
if (inRange(ppair.mass(), 81.2*GeV, 101.2*GeV)) vetoEvent;
// check triplets with muon
for (size_t iz = 0; iz < recon_mu.size(); ++iz) {
if (iz==ix || iz==iy) continue;
if (inRange((ppair+recon_mu[iz].momentum()).mass(), 81.2*GeV, 101.2*GeV)) vetoEvent;
}
// check triplets with electron
for (size_t iz = 0; iz < recon_e.size(); ++iz) {
if (inRange((ppair+recon_e[iz].momentum()).mass(), 81.2*GeV, 101.2*GeV)) vetoEvent;
}
// check muon quadruplets
for (size_t iz = 0; iz < recon_mu.size(); ++iz) {
for (size_t iw = iz+1; iy < recon_mu.size(); ++iy) {
if (iz==ix || iz==iy || iw==ix || iw==iy) continue;
if (recon_mu[iz].pid()*recon_mu[iw].pid() > 0) continue;
if (inRange((ppair+recon_mu[iz].momentum()+recon_mu[iw].momentum()).mass(), 81.2*GeV, 101.2*GeV)) vetoEvent;
}
}
}
}
// Make the control plots
_hist_etmiss->fill(eTmiss);
_hist_meff ->fill(meff );
// Finally the counts
if (eTmiss > 50*GeV) _count_SR1->fill(0.5);
if (meff >0*GeV) _count_SR2->fill(0.5);
}
/// @}
void finalize() {
double norm = crossSection()/femtobarn*13./sumOfWeights();
scale(_hist_etmiss,norm*20.);
scale(_hist_meff ,norm*20.);
scale(_count_SR1,norm);
scale(_count_SR2,norm);
}
private:
/// @name Histograms
/// @{
Histo1DPtr _hist_electrons;
Histo1DPtr _hist_muons;
Histo1DPtr _hist_leptons;
Histo1DPtr _hist_4leptons;
Histo1DPtr _hist_veto;
Histo1DPtr _hist_etmiss;
Histo1DPtr _hist_meff;
Histo1DPtr _count_SR1;
Histo1DPtr _count_SR2;
/// @}
};
RIVET_DECLARE_PLUGIN(ATLAS_2012_CONF_2012_153);
}