Rivet analyses
Search for supersymmetry with 2 same-sign leptons, jets and missing transverse energy
Experiment: ATLAS (LHC)
Inspire ID: 1204312
Status: OBSOLETE
Authors: - Peter Richardson
References: - Expt page: ATLAS-CONF-2012-105
Beams: p+ p+
Beam energies: (4000.0, 4000.0)GeV
Run details: - BSM signal events at 8000 GeV.
Results of the search for the production of supersymmetric particles decaying into final states with missing transverse momentum and two isolated same-sign leptons, electrons or muons. The analysis uses a data sample collected during the first half of 2012 that corresponds to a total integrated luminosity o1 5.8 fb−1 of $\sqrt{s} = 8$,TeV proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider. Opposite-sign and same-sign dilepton events are studied separately.
Source
code:ATLAS_2012_CONF_2012_105.cc
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/VisibleFinalState.hh"
#include "Rivet/Projections/IdentifiedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/VetoedFinalState.hh"
namespace Rivet {
class ATLAS_2012_CONF_2012_105 : public Analysis {
public:
/// Constructor
ATLAS_2012_CONF_2012_105()
: Analysis("ATLAS_2012_CONF_2012_105")
{ }
/// @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 > 20*GeV);
elecs.acceptIdPair(PID::ELECTRON);
declare(elecs, "elecs");
// projection to find the muons
IdentifiedFinalState muons(Cuts::abseta < 2.4 && Cuts::pT > 20*GeV);
muons.acceptIdPair(PID::MUON);
declare(muons, "muons");
// jet finder
VetoedFinalState vfs;
vfs.addVetoPairId(PID::MUON);
declare(FastJets(vfs, JetAlg::ANTIKT, 0.4), "AntiKtJets04");
// all tracks (to do deltaR with leptons)
declare(ChargedFinalState(Cuts::abseta < 3 && Cuts::pT > 0.5*GeV), "cfs");
// for pTmiss
declare(VisibleFinalState(Cuts::abseta < 4.5), "vfs");
// book histograms
// counts in signal regions
book(_count_ee ,"count_ee" , 1, 0., 1.);
book(_count_emu ,"count_emu" , 1, 0., 1.);
book(_count_mumu ,"count_mumu", 1, 0., 1.);
book(_count_ll ,"count_ll" , 1, 0., 1.);
// histograms from paper
book(_hist_eTmiss_ee ,"eTmiss_ee" , 8, 0., 400.);
book(_hist_eTmiss_emu ,"eTmiss_emu" , 8, 0., 400.);
book(_hist_eTmiss_mumu ,"eTmiss_mumu", 8, 0., 400.);
book(_hist_eTmiss_ll ,"eTmiss_ll" , 8, 0., 400.);
}
/// Perform the event analysis
void analyze(const Event& event) {
// get the jet candidates
Jets cand_jets = apply<FastJets>(event, "AntiKtJets04").jetsByPt(Cuts::abseta < 2.8 && Cuts::pT > 20*GeV);
// electron candidates
Particles cand_e = apply<IdentifiedFinalState>(event, "elecs").particlesByPt();
// Discard jets that overlap with electrons
Jets recon_jets;
for ( const Jet& jet : cand_jets ) {
bool away_from_e = true;
for ( const Particle & e : cand_e ) {
if ( deltaR(e.momentum(),jet.momentum()) <= 0.2 ) {
away_from_e = false;
break;
}
}
if ( away_from_e ) recon_jets.push_back( jet );
}
// get the charged tracks for isolation
Particles chg_tracks =
apply<ChargedFinalState>(event, "cfs").particles();
// Reconstructed electrons
Particles recon_leptons;
for ( const Particle & e : cand_e ) {
// check not near a jet
bool e_near_jet = false;
for ( const Jet& jet : recon_jets ) {
if ( deltaR(e.momentum(),jet.momentum()) < 0.4 ) {
e_near_jet = true;
break;
}
}
if ( e_near_jet ) continue;
// check the isolation
double pTinCone = -e.pT();
for ( const Particle & track : chg_tracks ) {
if ( deltaR(e.momentum(),track.momentum()) < 0.2 )
pTinCone += track.pT();
}
if ( pTinCone < 0.1*e.perp() )
recon_leptons.push_back(e);
}
// Reconstructed Muons
Particles cand_mu =
apply<IdentifiedFinalState>(event,"muons").particlesByPt();
for ( const Particle & mu : cand_mu ) {
// check not near a jet
bool mu_near_jet = false;
for ( const Jet& jet : recon_jets ) {
if ( deltaR(mu.momentum(),jet.momentum()) < 0.4 ) {
mu_near_jet = true;
break;
}
}
if ( mu_near_jet ) continue;
// isolation
double pTinCone = -mu.pT();
for ( const Particle & track : chg_tracks ) {
if ( deltaR(mu.momentum(),track.momentum()) < 0.2 )
pTinCone += track.pT();
}
if ( pTinCone < 1.8*GeV )
recon_leptons.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();
// Exactly two leptons for each event
if ( recon_leptons.size() != 2) vetoEvent;
// ensure 1st hardest
if(recon_leptons[0].perp()<recon_leptons[1].perp())
std::swap(recon_leptons[0],recon_leptons[1]);
// only keep same sign
if(recon_leptons[0].pid()*recon_leptons[1].pid()<0)
vetoEvent;
// at least 4 jets pt>50
if(recon_jets.size()<4||recon_jets[3].perp()<50.)
vetoEvent;
if(recon_leptons[0].pid()!=recon_leptons[1].pid())
_hist_eTmiss_emu ->fill(eTmiss);
else if(recon_leptons[0].abspid()==PID::ELECTRON)
_hist_eTmiss_ee ->fill(eTmiss);
else if(recon_leptons[0].abspid()==PID::MUON)
_hist_eTmiss_mumu->fill(eTmiss);
_hist_eTmiss_ll->fill(eTmiss);
if(eTmiss>150.) {
if(recon_leptons[0].pid()!=recon_leptons[1].pid())
_count_emu ->fill(0.5);
else if(recon_leptons[0].abspid()==PID::ELECTRON)
_count_ee ->fill(0.5);
else if(recon_leptons[0].abspid()==PID::MUON)
_count_mumu->fill(0.5);
_count_ll->fill(0.5);
}
}
/// @}
void finalize() {
double norm = crossSection()/femtobarn*5.8/sumOfWeights();
// event counts
scale(_count_ee ,norm);
scale(_count_emu ,norm);
scale(_count_mumu,norm);
scale(_count_ll ,norm);
// histograms
scale(_hist_eTmiss_ee ,norm*50.);
scale(_hist_eTmiss_emu ,norm*50.);
scale(_hist_eTmiss_mumu,norm*50.);
scale(_hist_eTmiss_ll ,norm*50.);
}
private:
/// @name Histograms
/// @{
Histo1DPtr _count_ee ;
Histo1DPtr _count_emu ;
Histo1DPtr _count_mumu;
Histo1DPtr _count_ll ;
Histo1DPtr _hist_eTmiss_ee;
Histo1DPtr _hist_eTmiss_emu;
Histo1DPtr _hist_eTmiss_mumu;
Histo1DPtr _hist_eTmiss_ll;
/// @}
};
RIVET_DECLARE_PLUGIN(ATLAS_2012_CONF_2012_105);
}