Rivet analyses
Search for SUSY in 13~events with 2 or 3 leptons and multiple jets
Experiment: ATLAS (LHC)
Inspire ID: 1479668
Status: UNVALIDATED
Authors: - Andy Buckley
References: none listed
Beams: p+ p+
Beam energies: (6500.0, 6500.0)GeV
Run details: - BSM signal events
A search for strongly produced supersymmetric particles using signatures involving multiple energetic jets and either two isolated same-sign leptons (e or μ) or at least three isolated leptons. The analysis also utilises other observables, such as b-tagged jets or missing transverse momentum, to extend its sensitivity. A data sample of proton–proton collisions at $\sqrt{s} = 13~\TeV$ recorded with the ATLAS detector at the Large Hadron Collider in 2015 and 2016, corresponding to a total integrated luminosity of 13.2/fb, is used for the search. No significant excess over the Standard Model expectation is observed.
Source
code:ATLAS_2016_CONF_2016_037.cc
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/PromptFinalState.hh"
#include "Rivet/Projections/SmearedJets.hh"
#include "Rivet/Projections/SmearedMET.hh"
#include "Rivet/Projections/SmearedParticles.hh"
#include "Rivet/Projections/Sphericity.hh"
namespace Rivet {
/// @brief ATLAS 2016 2 -SS-lepton / 3-lepton SUSY search, from 13.2/fb CONF note
class ATLAS_2016_CONF_2016_037 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2016_CONF_2016_037);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
FinalState calofs(Cuts::abseta < 4.9);
declare(calofs, "Clusters");
FastJets fj(calofs, JetAlg::ANTIKT, 0.4);
declare(fj, "TruthJets");
declare(SmearedJets(fj, JET_SMEAR_ATLAS_RUN2,
[](const Jet& j) {
if (j.abseta() > 2.5) return 0.;
return j.bTagged(Cuts::pT > 5 * GeV) ? 0.70
: j.cTagged(Cuts::pT > 5 * GeV) ? 1 / 12.
: j.tauTagged(Cuts::pT > 5 * GeV) ? 1 / 54.
: 1 / 380.;
}),
"Jets");
MissingMomentum mm(calofs);
declare(mm, "TruthMET");
declare(SmearedMET(mm, MET_SMEAR_ATLAS_RUN2), "MET");
FinalState es(Cuts::abspid == PID::ELECTRON && Cuts::abseta < 2.47 && !Cuts::absetaIn(1.37, 1.52)
&& Cuts::pT > 10 * GeV);
declare(es, "TruthElectrons");
declare(SmearedParticles(es, ELECTRON_RECOEFF_ATLAS_RUN2, ELECTRON_SMEAR_ATLAS_RUN2), "Electrons");
FinalState mus(Cuts::abspid == PID::MUON && Cuts::abseta < 2.5 && Cuts::pT > 10 * GeV);
declare(mus, "TruthMuons");
declare(SmearedParticles(mus, MUON_EFF_ATLAS_RUN2_MEDIUM, MUON_SMEAR_ATLAS_RUN2), "Muons");
FinalState cfs(Cuts::abseta < 2.5 && Cuts::abscharge > 0);
declare(cfs, "TruthTracks");
declare(SmearedParticles(cfs, TRK_EFF_ATLAS_RUN2), "Tracks");
// Book histograms/counters
book(_h_3l1, "SR3l1");
book(_h_3l2, "SR3l2");
book(_h_0b1, "SR0b1");
book(_h_0b2, "SR0b2");
book(_h_1b, "SR1b");
book(_h_3b, "SR3b");
book(_h_1bDD, "SR1bDD");
book(_h_3bDD, "SR3bDD");
book(_h_1bGG, "SR1bGG");
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// Get baseline electrons, muons, and jets
Particles elecs = apply<ParticleFinder>(event, "Electrons").particlesByPt();
Particles muons = apply<ParticleFinder>(event, "Muons").particlesByPt();
Jets jets = apply<JetFinder>(event, "Jets").jetsByPt(Cuts::pT > 20 * GeV && Cuts::abseta < 2.8);
const Jets bjets = select(jets, [&](const Jet& j) { return j.bTagged(Cuts::pT > 5 * GeV); });
// Jet/electron/muon overlap removal and selection
// Remove any electron or muon within dR = 0.2 of a b-tagged jet
for (const Jet& bj : bjets) {
idiscard(elecs, deltaRLess(bj, 0.2, RAPIDITY));
idiscard(muons, deltaRLess(bj, 0.2, RAPIDITY));
}
// Remove any untagged jet within dR = 0.2 of an electron or muon
for (const Particle& e : elecs) idiscard(jets, deltaRLess(e, 0.2, RAPIDITY));
for (const Particle& m : muons) idiscard(jets, deltaRLess(m, 0.2, RAPIDITY));
// Remove any untagged low-multiplicity/muon-dominated jet within dR = 0.4 of a muon
for (const Particle& m : muons)
idiscard(jets, [&](const Jet& j) {
if (deltaR(m, j, RAPIDITY) > 0.4) return false;
const Particles trks = j.particles(Cuts::abscharge != 0);
if (trks.size() < 3) return true;
return m.pT() / j.pT() > 0.5 && m.pT() / sum(trks, pT, 0.0) > 0.7;
});
// Remove any electron or muon near a remaining jet, with a shrinking cone
const auto lcone_iso_fn = [&](const Particle& l) {
const double dr = min(0.4, 0.04 + 10 * GeV / l.pT());
return any(jets, deltaRLess(l, dr, RAPIDITY));
};
idiscard(elecs, lcone_iso_fn);
idiscard(muons, lcone_iso_fn);
// Track-sharing e,mu also filtered, but that decision can't be made here
const Jets& sigjets = jets;
const Jets& sigbjets = bjets;
// Lepton isolation
Particles sigelecs = select(elecs, Cuts::abseta < 2);
Particles sigmuons = muons;
iselect(sigelecs, ParticleEffFilter(ELECTRON_EFF_ATLAS_RUN2_MEDIUM));
const Particles trks = apply<ParticleFinder>(event, "Tracks").particles();
const Particles clus = apply<ParticleFinder>(event, "Clusters").particles();
idiscard(sigelecs, [&](const Particle& e) {
const double R = min(0.2, 10 * GeV / e.pT());
double ptsum = -e.pT(), etsum = -e.Et();
for (const Particle& t : trks)
if (deltaR(t, e) < R) ptsum += t.pT();
for (const Particle& c : clus)
if (deltaR(c, e) < 0.2) etsum += c.pT(); ///< @todo Bit vague about "energy"
return ptsum / e.pT() > 0.06 || etsum / e.pT() > 0.06;
});
idiscard(sigmuons, [&](const Particle& m) {
const double R = min(0.3, 10 * GeV / m.pT());
double ptsum = -m.pT();
for (const Particle& t : trks)
if (deltaR(t, m) < R) ptsum += t.pT();
return ptsum / m.pT() > 0.06;
});
/// @todo Note is vague about whether "signal lepton" defn includes pT > 20?
idiscard(sigelecs, Cuts::pT > 20 * GeV);
idiscard(sigmuons, Cuts::pT > 20 * GeV);
// MET calculation (NB. done generically, with smearing, rather than via explicit physics objects)
const Vector3 vmet = -apply<SmearedMET>(event, "MET").vectorEt();
const double etmiss = vmet.mod();
//////////////////
// Event selection cuts
const Particles sigleptons = sigelecs + sigmuons;
if (sigleptons.size() < 2) vetoEvent;
if (sigleptons.size() == 2 && sigleptons[0].charge() != sigleptons[1].charge()) vetoEvent;
// Jet sub-selections and meff calculation
const Jets sigjets25 = select(sigjets, Cuts::pT > 25 * GeV);
const Jets sigjets40 = select(sigjets25, Cuts::pT > 40 * GeV);
const Jets sigjets50 = select(sigjets40, Cuts::pT > 50 * GeV);
/// @todo Is meff specific to the jet pT cut?
const double meff = sum(sigjets, pT, 0.0) + sum(sigleptons, pT, 0.0);
// Fill counters
if (sigleptons.size() >= 3 && sigbjets.empty() && sigjets40.size() >= 4 && etmiss > 150 * GeV)
_h_3l1->fill();
if (sigleptons.size() >= 3 && sigbjets.empty() && sigjets40.size() >= 4 && etmiss > 200 * GeV
&& meff > 1500 * GeV)
_h_3l2->fill();
if (sigleptons.size() >= 2 && sigbjets.empty() && sigjets25.size() >= 6 && etmiss > 150 * GeV
&& meff > 500 * GeV)
_h_0b1->fill();
if (sigleptons.size() >= 2 && sigbjets.empty() && sigjets40.size() >= 6 && etmiss > 150 * GeV
&& meff > 900 * GeV)
_h_0b2->fill();
if (sigleptons.size() >= 2 && sigbjets.size() >= 1 && sigjets25.size() >= 6 && etmiss > 200 * GeV
&& meff > 650 * GeV)
_h_1b->fill();
if (sigleptons.size() >= 2 && sigbjets.size() >= 3 && sigjets25.size() >= 6 && etmiss > 150 * GeV
&& meff > 600 * GeV)
_h_3b->fill();
if (select(sigleptons, Cuts::charge < 0).size() >= 2) {
if (sigleptons.size() >= 2 && sigbjets.size() >= 1 && sigjets50.size() >= 6 && meff > 1200 * GeV)
_h_1bDD->fill();
if (sigleptons.size() >= 2 && sigbjets.size() >= 3 && sigjets50.size() >= 6 && meff > 1000 * GeV)
_h_3bDD->fill();
if (sigleptons.size() >= 2 && sigbjets.size() >= 1 && sigjets50.size() >= 6 && meff > 1800 * GeV)
_h_1bGG->fill();
}
}
/// Normalise counters after the run
void finalize() {
const double sf = 13.2 * crossSection() / femtobarn / sumOfWeights();
scale(_h_3l1, sf);
scale(_h_3l2, sf);
scale(_h_0b1, sf);
scale(_h_0b2, sf);
scale(_h_1b, sf);
scale(_h_3b, sf);
scale(_h_1bDD, sf);
scale(_h_3bDD, sf);
scale(_h_1bGG, sf);
}
/// @}
private:
/// @name Histograms
/// @{
CounterPtr _h_3l1, _h_3l2, _h_0b1, _h_0b2, _h_1b, _h_3b, _h_1bDD, _h_3bDD, _h_1bGG;
/// @}
};
RIVET_DECLARE_PLUGIN(ATLAS_2016_CONF_2016_037);
}