A search for supersymmetry (SUSY) in events with large missing transverse momentum, jets, and at least one hadronically decaying tau lepton, with zero or one additional light lepton (e/mu), has been performed using 4.7 fb-1 of proton-proton collision data at sqrt(s) = 7 TeV recorded with the ATLAS detector at the Large Hadron Collider. No excess above the Standard Model background expectation is observed and a 95% confidence level visible cross-section upper limit for new phenomena is set. In the framework of gauge-mediated SUSY-breaking models, lower limits on the mass scale Lambda are set at 54 TeV in the regions where the stau is the next-to-lightest SUSY particle (tan(beta) > 20). These limits provide the most stringent tests to date of GMSB models in a large part of the parameter space considered.
The observed number of signal events as a function of Lambda and Tan(Beta).
The Acceptance, Efficiency and Acceptance x Efficiency for the single tau channel as a function of Lambda and Tan(Beta).
The Acceptance, Efficiency and Acceptance x Efficiency for the two tau channel as a function of Lambda and Tan(Beta).
The results of a search for supersymmetry in events with large missing transverse momentum and heavy flavour jets using an integrated luminosity corresponding to 2.05 fb^-1 of pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the Large Hadron Collider are reported. No significant excess is observed with respect to the prediction for Standard Model processes. Results are interpreted in a variety of R-parity conserving models in which scalar bottoms and tops are the only scalar quarks to appear in the gluino decay cascade, and in an SO(10) model framework. Gluino masses up to 600-900 GeV are excluded, depending on the model considered.
Acceptance in the GLUINO-NEUTRALINO plane in the Gbb model for the 1 btag signal region with Meff > 500 GeV.
Acceptance in the GLUINO-NEUTRALINO plane in the Gbb model for the 2 btags signal region with Meff > 500 GeV.
Acceptance in the GLUINO-NEUTRALINO plane in the Gbb model for the 1 btag signal region with Meff > 700 GeV.
A search for new phenomena in final states with four or more leptons (electrons or muons) is presented. The analysis is based on 4.7 fb^-1 of sqrt(s) = 7 TeV proton-proton collisions delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in two signal regions: one that requires moderate values of missing transverse momentum and another that requires large effective mass. The results are interpreted in a simplified model of R-parity-violating supersymmetry in which a 95% CL exclusion region is set for charged wino masses up to 540 GeV. In an R-parity-violating MSUGRA/CMSSM model, values of m_1/2 up to 820 GeV are excluded for 10<tan(beta)<40.
The transverse momentum distribution of the leading lepton for events with at least 4 leptons and no Z-boson candidate.
The transverse momentum distribution of the sub-leading lepton for events with at least 4 leptons and no Z-boson candidate.
The transverse momentum distribution of the 3rd-leading lepton for events with at least 4 leptons and no Z-boson candidate.
Two searches for supersymmetric particles in final states containing a same-flavour opposite-sign lepton pair, jets and large missing transverse momentum are presented. The proton-proton collision data used in these searches were collected at a centre-of-mass energy $\sqrt{s}=8$ TeV by the ATLAS detector at the Large Hadron Collider and corresponds to an integrated luminosity of 20.3 fb$^{-1}$. Two leptonic production mechanisms are considered: decays of squarks and gluinos with $Z$ bosons in the final state, resulting in a peak in the dilepton invariant mass distribution around the $Z$-boson mass; and decays of neutralinos (e.g. $\tilde{\chi}^{0}_{2} \rightarrow \ell^{+}\ell^{-}\tilde{\chi}^{0}_{1}$), resulting in a kinematic endpoint in the dilepton invariant mass distribution. For the former, an excess of events above the expected Standard Model background is observed, with a significance of 3 standard deviations. In the latter case, the data are well-described by the expected Standard Model background. The results from each channel are interpreted in the context of several supersymmetric models involving the production of squarks and gluinos.
The observed and expected dielectron invariant mass distribution in SR-Z. The negigible estimated contribution from Z+jets is omitted in these distributions.
The observed and expected dimuon invariant mass distribution in SR-Z. The negigible estimated contribution from Z+jets is omitted in these distributions.
The observed and expected $E_T^{miss}$ distribution in the dielectron SR-Z. The negigible estimated contribution from Z+jets is omitted in these distributions. The last bin contains the overflow.
Results from a search for supersymmetry in events with four or more leptons including electrons, muons and taus are presented. The analysis uses a data sample corresponding to 20.3 $fb^{-1}$ of proton--proton collisions delivered by the Large Hadron Collider at $\sqrt{s}$ = 8 TeV and recorded by the ATLAS detector. Signal regions are designed to target supersymmetric scenarios that can be either enriched in or depleted of events involving the production of a $Z$ boson. No significant deviations are observed in data from Standard Model predictions and results are used to set upper limits on the event yields from processes beyond the Standard Model. Exclusion limits at the 95% confidence level on the masses of relevant supersymmetric particles are obtained. In R-parity-violating simplified models with decays of the lightest supersymmetric particle to electrons and muons, limits of 1350 GeV and 750 GeV are placed on gluino and chargino masses, respectively. In R-parity-conserving simplified models with heavy neutralinos decaying to a massless lightest supersymmetric particle, heavy neutralino masses up to 620 GeV are excluded. Limits are also placed on other supersymmetric scenarios.
The ETmiss distribution in VR0Z.
The effective mass distribution in VR0Z.
The ETmiss distribution in VR2Z.
A search for strongly produced supersymmetric particles is conducted using signatures involving multiple energetic jets and either two isolated leptons ($e$ or $\mu$) with the same electric charge, or at least three isolated leptons. The search also utilises jets originating from b-quarks, missing transverse momentum and other observables to extend its sensitivity. The analysis uses a data sample corresponding to a total integrated luminosity of 20.3 fb$^{-1}$ of $\sqrt{s} =$ 8 TeV proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider in 2012. No deviation from the Standard Model expectation is observed. New or significantly improved exclusion limits are set on a wide variety of supersymmetric models in which the lightest squark can be of the first, second or third generations, and in which R-parity can be conserved or violated.
Numbers of observed and background events for SR0b for each bin of the distribution in Meff. The table corresponds to Fig. 4(b). The statistical and systematic uncertainties are combined for the expected backgrounds.
Numbers of observed and background events for SR1b for each bin of the distribution in Meff. The table corresponds to Fig. 4(c). The statistical and systematic uncertainties are combined for the predicted numbers.
Numbers of observed and background events for SR3b for each bin of the distribution in Meff. The table corresponds to Fig. 4(a). The statistical and systematic uncertainties are combined for the predicted numbers.
A search for strongly produced supersymmetric particles is conducted using signatures involving multiple energetic jets and either two isolated leptons ($e$ or $\mu$) with the same electric charge or at least three isolated leptons. The search also utilises $b$-tagged jets, missing transverse momentum and other observables to extend its sensitivity. The analysis uses a data sample of proton-proton collisions at $\sqrt{s}=13$ TeV recorded with the ATLAS detector at the Large Hadron Collider in 2015 corresponding to a total integrated luminosity of 3.2 fb$^{-1}$. No significant excess over the Standard Model expectation is observed. The results are interpreted in several simplified supersymmetric models and extend the exclusion limits from previous searches. In the context of exclusive production and simplified decay modes, gluino masses are excluded at 95% confidence level up to 1.1-1.3 TeV for light neutralinos (depending on the decay channel), and bottom squark masses are also excluded up to 540 GeV. In the former scenarios, neutralino masses are also excluded up to 550-850 GeV for gluino masses around 1 TeV.
Missing transverse momentum distribution after SR0b3j selection, beside the $E_\mathrm{T}^\mathrm{miss}$ requirement. The results in the signal region correspond to the last inclusive bin. The systematic uncertainties include theory uncertainties for the backgrounds with prompt SS/3L and the full systematic uncertainties for data-driven backgrounds. For illustration the distribution for a benchmark SUSY scenario ($pp\to \tilde g\tilde g$, $\tilde g\to qq(\tilde\ell\ell/\tilde\nu\nu)$, $m_{\tilde g}=1.3$ TeV, $m_{\tilde\chi_1^0}=0.5$ TeV) is also shown.
Missing transverse momentum distribution after SR0b5j selection, beside the $E_\mathrm{T}^\mathrm{miss}$ requirement. The results in the signal region correspond to the last inclusive bin. The systematic uncertainties include theory uncertainties for the backgrounds with prompt SS/3L and the full systematic uncertainties for data-driven backgrounds. For illustration the distribution for a benchmark SUSY scenario ($pp\to \tilde g\tilde g$, $\tilde g\to qqWZ\tilde\chi_1^0$, $m_{\tilde g}=1.1$ TeV, $m_{\tilde\chi_1^0}=0.4$ TeV) is also shown.
Missing transverse momentum distribution after SR1b selection, beside the $E_\mathrm{T}^\mathrm{miss}$ requirement. The results in the signal region correspond to the last inclusive bin. The systematic uncertainties include theory uncertainties for the backgrounds with prompt SS/3L and the full systematic uncertainties for data-driven backgrounds. For illustration the distribution for a benchmark SUSY scenario ($pp\to \tilde b_1\tilde b_1^*$, $\tilde b_1\to tW\tilde\chi_1^0$, $m_{\tilde b_1}=600$ GeV, $m_{\tilde\chi_1^0}=50$ GeV) is also shown.
A search for supersymmetry (SUSY) in events with large missing transverse momentum, jets, at least one hadronically decaying tau lepton and zero or one additional light leptons (electron/muon), has been performed using 20.3 fb$^{-1}$ of proton-proton collision data at $\sqrt{s} = 8$ TeV recorded with the ATLAS detector at the Large Hadron Collider. No excess above the Standard Model background expectation is observed in the various signal regions and 95% confidence level upper limits on the visible cross section for new phenomena are set. The results of the analysis are interpreted in several SUSY scenarios, significantly extending previous limits obtained in the same final states. In the framework of minimal gauge-mediated SUSY breaking models, values of the SUSY breaking scale $\Lambda$ below 63 TeV are excluded, independently of tan$\beta$. Exclusion limits are also derived for an mSUGRA/CMSSM model, in both the R-parity-conserving and R-parity-violating case. A further interpretation is presented in a framework of natural gauge mediation, in which the gluino is assumed to be the only light coloured sparticle and gluino masses below 1090 GeV are excluded.
Distribution of MTtau after all analysis requirements but the requirement on MTtau and the final requirement on HT for the 1tau ''Loose'' SR. The SM prediction includes the data-driven corrections discussed in the paper. MC events are normalized to data in the CRs corresponding to MTtau below 130 GeV. Also shown is the expected signal from typical mSUGRA, GMSB and bRPV samples. The last bin in the expected background distribution is an overflow bin.
Distribution of HT after the MTtau requirement for the 1-tau ''Loose'' SR. The SM prediction includes the data-driven corrections discussed in the paper. MC events are normalized to data in the CRs corresponding to MTtau below 130 GeV. Also shown is the expected signal from typical mSUGRA, GMSB and bRPV samples. The last bin in the expected background distribution is an overflow bin.
Distribution of MTtau after all analysis requirements but the requirement on MTtau and the final requirement on HT for the 1tau 'Tight'' SR. The SM prediction includes the data-driven corrections discussed in the paper. MC events are normalized to data in the CRs corresponding to MTtau below 130 GeV. Also shown is the expected signal from typical mSUGRA, GMSB and bRPV samples. The last bin in the expected background distribution is an overflow bin.
A search is presented for photonic signatures motivated by generalised models of gauge-mediated supersymmetry breaking. This search makes use of $20.3{\rm fb}^{-1}$ of proton-proton collision data at $\sqrt{s}=8$ TeV recorded by the ATLAS detector at the LHC, and explores models dominated by both strong and electroweak production of supersymmetric partner states. Four experimental signatures incorporating an isolated photon and significant missing transverse momentum are explored. These signatures include events with an additional photon, lepton, $b$-quark jet, or jet activity not associated with any specific underlying quark flavor. No significant excess of events is observed above the Standard Model prediction and model-dependent 95% confidence-level exclusion limits are set.
Observed and expected exclusion limits in the gluino-bino mass plane, using the $\rm{SR}^{\gamma\gamma}_{S-H}$ analysis for $m_{\tilde{\chi}_1^0}\geq 800 {\rm GeV}$ and $\rm{SR}^{\gamma\gamma}_{S-L}$ analyses for $m_{\tilde{\chi}_1^0} < 800 {\rm GeV}$.
Observed and expected exclusion limits in the wino-bino mass plane, using the $\rm{SR}^{\gamma\gamma}_{W-H}$ analysis for $m_{\tilde{\chi}_1^0}\geq 350 {\rm GeV}$ and $\rm{SR}^{\gamma\gamma}_{W-L}$ analyses for $m_{\tilde{\chi}_1^0} < 350 {\rm GeV}$.
Observed exclusion limits in the gluino-neutralino mass plane, for the higgsino-bino GGM model with $\mu < 0$, using the merged $\rm{SR}^{\gamma b}_{L}$ and $\rm{SR}^{\gamma b}_{H}$ analyses.
A search has been performed for the experimental signature of an isolated photon with high transverse momentum, at least one jet identified as originating from a bottom quark, and high missing transverse momentum. Such a final state may originate from supersymmetric models with gauge-mediated supersymmetry breaking in events in which one of a pair of higgsino-like neutralinos decays into a photon and a gravitino while the other decays into a Higgs boson and a gravitino. The search is performed using the full dataset of 7 TeV proton-proton collisions recorded with the ATLAS detector at the LHC in 2011, corresponding to an integrated luminosity of 4.7 fb-1. A total of 7 candidate events are observed while 7.5 pm 2.2 events are expected from the Standard Model background. The results of the search are interpreted in the context of general gauge mediation to exclude certain regions of a benchmark plane for higgsino-like neutralino production.
Missing ET distribution.
Signal Point Information: (1) Number of Monte Carlo events generated (2) Total signal cross section (pb) (3) Signal acceptance (4) Relative uncertainty on acceptance (5) CLs expected (6) CLs observed.
The observed limit contour in the GLUINO-NEUTRALINO plane.
Results are presented of a search for supersymmetric particles in events with large missing transverse momentum and at least one heavy flavour jet candidate in sqrt{s} = 7 TeV proton-proton collisions. In a data sample corresponding to an integrated luminosity of 35 pb-1 recorded by the ATLAS experiment at the Large Hadron Collider, no significant excess is observed with respect to the prediction for Standard Model processes. For R-parity conserving models in which sbottoms (stops) are the only squarks to appear in the gluino decay cascade, gluino masses below 590 GeV (520 GeV) are excluded at the 95% C.L. The results are also interpreted in an MSUGRA/CMSSM supersymmetry breaking scenario with tan(beta)=40 and in an SO(10) model framework.
Distribution of the effective mass for data and the SM expectation in the zero-lepton plus 3 jet channel.
Distribution of the missing ET for data and the SM expectation in the zero-lepton plus 3 jet channel.
Distribution of the effective mass for data and the SM expectation in the one-lepton plus 2 jet channel.
The results of a search for supersymmetric particles in final states with four or more leptons (electrons or muons) and missing transverse momentum with the ATLAS detector are presented. The analysis uses a sample corresponding to an integrated luminosity of 2.06 fb−1 of proton-proton data recorded in 2011 at a centre-of-mass energy of 7 TeV. With an inclusive selection four events are observed, while 1.7±0.9 are expected from Standard Model processes. After applying a Z boson veto for leptons pairs with the same flavour and opposite charge, no events are observed for 0.7±0.8 events expected. Within the selection acceptance, we determine 95% C.L. visible cross-section upper limits for new phenomena of 3.5 fb and 1.5 fb for the selections without and with the Z-veto, respectively.
Transverse momentum(energy) distribution of the leading muon(electron) for events with at least 4 leptons each having transverse PT(ET) > 10 GeV.
Transverse momentum(energy) distribution of the second leading muon(electron) for events with at least 4 leptons each having transverse PT(ET) > 10 GeV.
Transverse momentum(energy) distribution of the third leading muon(electron) for events with at least 4 leptons each having transverse PT(ET) > 10 GeV.
Results of three searches are presented for the production of supersymmetric particles decaying into final states with missing transverse momentum and exactly two isolated leptons, e or mu. The analysis uses a data sample collected during the first half of 2011 that corresponds to a total integrated luminosity of 1 fb^-1 of sqrt{s} = 7 TeV proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider. Opposite-sign and same-sign dilepton events are separately studied, with no deviations from the Standard Model expectation observed. Additionally, in opposite- sign events, a search is made for an excess of same-flavour over different-flavour lepton pairs. Effective production cross sections in excess of 9.9 fb for opposite-sign events containing supersymmetric particles with missing transverse momentum greater than 250 GeV are excluded at 95% CL. For same-sign events containing supersymmetric particles with missing transverse momentum greater than 100 GeV, effective production cross sections in excess of 14.8 fb are excluded at 95% CL. The latter limit is interpreted in a simplified weak gaugino production model excluding chargino masses up to 200 GeV.
The dilepton invariant mass distribution for same-sign dileptons.
The missing-mass ET distribution for same-sign dilepton events before any jet requirement.
The missing-mass ET distribution for same-sign dilepton events after requiring two high-pt jets.
In models of anomaly-mediated supersymmetry breaking (AMSB), the lightest chargino is predicted to have a lifetime long enough to be detected in collider experiments. This letter explores AMSB scenarios in pp collisions at sqrt(s) = 7 TeV by attempting to identify decaying charginos which result in tracks that appear to have few associated hits in the outer region of the tracking system. The search was based on data corresponding to an integrated luminosity of 1.02 fb^-1 collected with the ATLAS detector in 2011. The pT spectrum of candidate tracks is found to be consistent with the expectation from Standard Model background processes and constraints on the lifetime and the production cross section were obtained. In the minimal AMSB framework with m_3/2 < 32 TeV, m_0 < 1.5 TeV, tan(beta) = 5 and mu > 0, a chargino having mass below 92 GeV and a lifetime between 0.5 ns and 2 ns is excluded at 95% confidence level.
The pT distribution of candidate tracks with the background prediction.
95% CL upper limits on the production cross section times acceptance as a function of the track pt threshold.
95% CL upper limits on the production cross section as a function of chargino lifetime for the chargino mass of 90.2 GeV.
The results of a search for pair production of the lighter scalar partners of top quarks in 2.05 fb-1 of pp collisions at sqrt(s) =7 TeV using the ATLAS experiment at the LHC are reported. Scalar top quarks are searched for in events with two same flavour opposite-sign leptons (electrons or muons) with invariant mass consistent with the Z boson mass, large missing transverse momentum and jets in the final state. At least one of the jets is identified as originating from a b-quark. No excess over Standard Model expectations is found. The results are interpreted in the framework of R-parity conserving, gauge mediated Supersymmetry breaking `natural' scenarios, where the neutralino is the next-to-lightest supersymmetric particle. Scalar top quark masses up to 310 GeV are excluded for the lightest neutralino mass between 115 GeV and 230 GeV at 95% confidence level, reaching an exclusion of the scalar top quark mass of 330 GeV for the lightest neutralino mass of 190 GeV. Scalar top quark masses below 240 GeV are excluded for all values of the lightest neutralino mass above the Z boson mass.
The missing ET distribution from the combined EE and MUMU data for SR1. Tabulated are the observed Data rates and the Standard Model predictions as well as the distributions expected for two signal scenarios, both with an STOP mass of 250 GeV, and NEUTRALINO1 masses of 100 GeV and 220 GeV respectively.
The number of b-tagged jets for SR1 for the combined EE and MUMU channels. Tabulated are the observed Data rates and the Standard Model predictions as well as the distributions expected for two signal scenarios, both with an STOP mass of 250 GeV, and NEUTRALINO1 masses of 100 GeV and 220 GeV respectively.
The distrubution of leading jet pT for SR1 for the combined EE and MUMU channels. Tabulated are the observed Data rates and the Standard Model predictions as well as the distributions expected for two signal scenarios, both with an STOP mass of 250 GeV, and NEUTRALINO1 masses of 100 GeV and 220 GeV respectively. The last pT bin includes the number of overflow events for both data abd SM expectation.
A search for production of supersymmetric particles in final states containing jets, missing transverse momentum, and at least one hadronically decaying tau lepton is presented. The data were recorded by the ATLAS experiment in sqrt(s) = 7 TeV proton-proton collisions at the Large Hadron Collider. No excess above the Standard Model background expectation was observed in 2.05 fb-1 of data. The results are interpreted in the context of gauge mediated supersymmetry breaking models with Mmess = 250 TeV, N5 = 3, mu > 0, and Cgrav = 1. The production of supersymmetric particles is excluded at 95% C.L. up to a supersymmetry breaking scale Lambda = 30 Tev, independent of tan(beta), and up to Lambda = 43 TeV for large tan(beta).
Distribution of the missing transverse energy before final selection requirement on the effective mass. Tabulated are the observed Data events, the Standard Model predictions and the expected rates for two signal scenarios with Lambda=30TeV / tan(beta) = 20 and Lambda=40GeV / tan(beta)=30 respectively.
Distribution of the tau pt before final selection requirement on the effective mass. Tabulated are the observed Data events, the Standard Model predictions and the expected rates for two signal scenarios with Lambda=30TeV / tan(beta) = 20 and Lambda=40GeV / tan(beta)=30 respectively.
Distribution of the effective mass before final selection requirement on the effective mass. Tabulated are the observed Data events, the Standard Model predictions and the expected rates for two signal scenarios with Lambda=30TeV / tan(beta) = 20 and Lambda=40GeV / tan(beta)=30 respectively.
A search for the weak production of charginos and neutralinos into final states with three electrons or muons and missing transverse momentum is presented. The analysis uses 2.06 fb^-1 of sqrt(s) = 7 TeV proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with standard model expectations in two signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric and simplified models. For the simplified models, degenerate lightest chargino and next-to-lightest neutralino masses up to 300 GeV are excluded for mass differences from the lightest neutralino up to 300 GeV.
Transverse momentum distribution for the first leading lepton for events in the SR1 signal region for DATA and SM predictions.
Transverse momentum distribution for the first leading lepton for events in the SR2 signal region for DATA and SM predictions.
Transverse momentum distribution for the second leading lepton for events in the SR1 signal region for DATA and SM predictions.
This Letter presents the first search for supersymmetry in final states containing one isolated electron or muon, jets, and missing transverse momentum from sqrt{s} = 7 TeV proton-proton collisions at the LHC. The data were recorded by the ATLAS experiment during 2010 and correspond to a total integrated luminosity of 35 pb-1. No excess above the standard model background expectation is observed. Limits are set on the parameters of the minimal supergravity framework, extending previous limits. For A_0 = 0 GeV, tan beta = 3, mu > 0 and for equal squark and gluino masses, gluino masses below 700 GeV are excluded at 95% confidence level.
Distribution of ET(C=MISSING) IN GEV for data and background MC calculation.
Distribution of MT IN GEV for data and background MC calculation.
Distribution of M(C=EFFECTIVE) IN GEV for data and background MC calculation.
A search for new phenomena in final states containing an $e^+e^-$ or $\mu^+\mu^-$ pair, jets, and large missing transverse momentum is presented. This analysis makes use of proton--proton collision data with an integrated luminosity of $36.1 \; \mathrm{fb}^{-1}$, collected during 2015 and 2016 at a centre-of-mass energy $\sqrt{s}$ = 13 TeV with the ATLAS detector at the Large Hadron Collider. The search targets the pair production of supersymmetric coloured particles (squarks or gluinos) and their decays into final states containing an $e^+e^-$ or $\mu^+\mu^-$ pair and the lightest neutralino ($\tilde{\chi}_1^0$) via one of two next-to-lightest neutralino ($\tilde{\chi}_2^0$) decay mechanisms: $\tilde{\chi}_2^0 \rightarrow Z \tilde{\chi}_1^0$, where the $Z$ boson decays leptonically leading to a peak in the dilepton invariant mass distribution around the $Z$ boson mass; and $\tilde{\chi}_2^0 \rightarrow \ell^+\ell^- \tilde{\chi}_1^0$ with no intermediate $\ell^+\ell^-$ resonance, yielding a kinematic endpoint in the dilepton invariant mass spectrum. The data are found to be consistent with the Standard Model expectation. Results are interpreted using simplified models, and exclude gluinos and squarks with masses as large as 1.85 TeV and 1.3 TeV at 95% confidence level, respectively.
Observed and expected dilepton mass distributions, with the bin boundaries considered for the interpretation, in SR-low. All statistical and systematic uncertainties of the expected background are included in the hatched band. An example signal from the slepton model with m(gluino) = 1200 GeV and m(neutralino1) = 900 GeV is overlaid.
Observed and expected dilepton mass distributions, with the bin boundaries considered for the interpretation, in SR-med. All statistical and systematic uncertainties of the expected background are included in the hatched band. An example signal from the slepton model with m(gluino) = 1600 GeV and m(neutralino1) = 900 GeV, and from an on-$Z$ model with m(gluino) = 1640 GeV and m(neutralino1) = 1160 GeV, is overlaid.
Observed and expected dilepton mass distributions, with the bin boundaries considered for the interpretation, in SR-high. All statistical and systematic uncertainties of the expected background are included in the hatched band. An example signal from the slepton model with m(gluino) = 1800 GeV and m(neutralino1) = 500 GeV, and from an on-$Z$ model with m(gluino) = 1650 GeV and m(neutralino1) = 550 GeV, is overlaid.
A search for the supersymmetric partners of the Standard Model bottom and top quarks is presented. The search uses 36.1 fb$^{-1}$ of $pp$ collision data at $\sqrt{s}=13$ TeV collected by the ATLAS experiment at the Large Hadron Collider. Direct production of pairs of bottom and top squarks ($\tilde{b}_{1}$ and $\tilde{t}_{1}$) is searched for in final states with $b$-tagged jets and missing transverse momentum. Distinctive selections are defined with either no charged leptons (electrons or muons) in the final state, or one charged lepton. The zero-lepton selection targets models in which the $\tilde{b}_{1}$ is the lightest squark and decays via $\tilde{b}_{1} \rightarrow b \tilde{\chi}^{0}_{1}$, where $\tilde{\chi}^{0}_{1}$ is the lightest neutralino. The one-lepton final state targets models where bottom or top squarks are produced and can decay into multiple channels, $\tilde{b}_{1} \rightarrow b \tilde{\chi}^{0}_{1}$ and $\tilde{b}_{1} \rightarrow t \tilde{\chi}^{\pm}_{1}$, or $\tilde{t}_{1} \rightarrow t \tilde{\chi}^{0}_{1}$ and $\tilde{t}_{1} \rightarrow b \tilde{\chi}^{\pm}_{1}$, where $\tilde{\chi}^{\pm}_{1}$ is the lightest chargino and the mass difference $m_{\tilde{\chi}^{\pm}_{1}}- m_{\tilde{\chi}^{0}_{1}}$ is set to 1 GeV. No excess above the expected Standard Model background is observed. Exclusion limits at 95\% confidence level on the mass of third-generation squarks are derived in various supersymmetry-inspired simplified models.
- - - - - - - - - - - - - - - - - - - - <br/><b>Acceptance:</b><br/><i>symmetric:</i> <a href="79165?version=1&table=Acceptance1">b0L-SRA350</a> <a href="79165?version=1&table=Acceptance2">b0L-SRA450</a> <a href="79165?version=1&table=Acceptance3">b0L-SRA550</a> <a href="79165?version=1&table=Acceptance4">b0L-SRB</a> <a href="79165?version=1&table=Acceptance5">b0L-SRC</a> <a href="79165?version=1&table=Acceptance6">b0L-best</a><br/><i>asymmetric:</i> <a href="79165?version=1&table=Acceptance7">b1L-SRA300-2j</a> <a href="79165?version=1&table=Acceptance8">b1L-SRA450</a> <a href="79165?version=1&table=Acceptance9">b1L-SRA600</a> <a href="79165?version=1&table=Acceptance10">b1L-SRA750</a> <a href="79165?version=1&table=Acceptance11">b1L-SRB</a> <a href="79165?version=1&table=Acceptance12">b1L-best</a><br/><br/><b>Efficiency:</b><br/><i>symmetric:</i> <a href="79165?version=1&table=Efficiency1">b0L-SRA350</a> <a href="79165?version=1&table=Efficiency2">b0L-SRA450</a> <a href="79165?version=1&table=Efficiency3">b0L-SRA550</a> <a href="79165?version=1&table=Efficiency4">b0L-SRB</a> <a href="79165?version=1&table=Efficiency5">b0L-SRC</a> <a href="79165?version=1&table=Efficiency6">b0L-best</a><br/><i>asymmetric:</i> <a href="79165?version=1&table=Efficiency7">b1L-SRA300-2j</a> <a href="79165?version=1&table=Efficiency8">b1L-SRA450</a> <a href="79165?version=1&table=Efficiency9">b1L-SRA600</a> <a href="79165?version=1&table=Efficiency10">b1L-SRA750</a> <a href="79165?version=1&table=Efficiency11">b1L-SRB</a> <a href="79165?version=1&table=Efficiency12">b1L-best</a><br/><br/><b>Best SR Mapping:</b><br/><i>symmetric:</i> <a href="79165?version=1&table=BestSR4">b0L</a><br/><i>asymmetric:</i> <a href="79165?version=1&table=BestSR1">b1L</a> <a href="79165?version=1&table=BestSR2">b0L</a> <a href="79165?version=1&table=BestSR3">combined</a><br/><br/><b>Exclusion Contour:</b><br/><i>symmetric:</i> b0L-SRA350 <a href="79165?version=1&table=Contour1">exp</a> <a href="79165?version=1&table=Contour2">obs</a> b0L-SRA450 <a href="79165?version=1&table=Contour5">exp</a> <a href="79165?version=1&table=Contour6">obs</a> b0L-SRA550 <a href="79165?version=1&table=Contour9">exp</a> <a href="79165?version=1&table=Contour10">obs</a> b0L-SRB <a href="79165?version=1&table=Contour11">exp</a> <a href="79165?version=1&table=Contour12">obs</a> b0L-SRC <a href="79165?version=1&table=Contour15">exp</a> <a href="79165?version=1&table=Contour16">obs</a> b0L-best <a href="79165?version=1&table=Contour17">exp</a> <a href="79165?version=1&table=Contour18">obs</a><br/><i>asymmetric:</i> b0L-SRA350 <a href="79165?version=1&table=Contour3">exp</a> <a href="79165?version=1&table=Contour4">obs</a> b0L-SRA450 <a href="79165?version=1&table=Contour7">exp</a> <a href="79165?version=1&table=Contour8">obs</a> b0L-SRB <a href="79165?version=1&table=Contour13">exp</a> <a href="79165?version=1&table=Contour14">obs</a> b0L-best <a href="79165?version=1&table=Contour19">exp</a> <a href="79165?version=1&table=Contour20">obs</a> b1L-SRA300-2j <a href="79165?version=1&table=Contour21">exp</a> <a href="79165?version=1&table=Contour22">obs</a> b1L-SRA450 <a href="79165?version=1&table=Contour23">exp</a> <a href="79165?version=1&table=Contour24">obs</a> b1L-SRA600 <a href="79165?version=1&table=Contour25">exp</a> <a href="79165?version=1&table=Contour26">obs</a> b1L-SRA750 <a href="79165?version=1&table=Contour27">exp</a> <a href="79165?version=1&table=Contour28">obs</a> b1L-SRB <a href="79165?version=1&table=Contour29">exp</a> <a href="79165?version=1&table=Contour30">obs</a> b1L-best <a href="79165?version=1&table=Contour31">exp</a> <a href="79165?version=1&table=Contour32">obs</a> A-LowMass <a href="79165?version=1&table=Contour33">exp</a> <a href="79165?version=1&table=Contour34">obs</a> A-HighMass <a href="79165?version=1&table=Contour35">exp</a> <a href="79165?version=1&table=Contour36">obs</a> B combination <a href="79165?version=1&table=Contour37">exp</a> <a href="79165?version=1&table=Contour38">obs</a> Best combination <a href="79165?version=1&table=Contour39">exp</a> <a href="79165?version=1&table=Contour40">obs</a><br/><br/><b>SR Distribution:</b><br/><a href="79165?version=1&table=SRdistribution1">b0L-SRA</a>: $m_{\mathrm{CT}}$ <a href="79165?version=1&table=SRdistribution2">b0L-SRB</a>: $\mathrm{min[m_{T}(jet_{1-4}, E_{T}^{miss})]}$ <a href="79165?version=1&table=SRdistribution3">b0L-SRC</a>: ${\cal A}$ <a href="79165?version=1&table=SRdistribution4">b1L-SRA300-2j</a>: $\mathrm{m_{bb}}$ <a href="79165?version=1&table=SRdistribution5">b1L-SRA</a>: $\mathrm{m_{eff}}$ <a href="79165?version=1&table=SRdistribution6">b1L-SRB</a>: $\mathrm{m_{T}}$<br/><br/><b>Cross section upper limit:</b><br/><i>symmetric:</i> <a href="79165?version=1&table=Limitoncrosssection1">b0L-best</a> <a href="79165?version=1&table=Limitoncrosssection2">b0L-SRA350</a> <a href="79165?version=1&table=Limitoncrosssection3">b0L-SRA450</a> <a href="79165?version=1&table=Limitoncrosssection4">b0L-SRA550</a> <a href="79165?version=1&table=Limitoncrosssection5">b0L-SRB</a> <a href="79165?version=1&table=Limitoncrosssection6">b0L-SRC</a><br/><i>asymmetric:</i> <a href="79165?version=1&table=Limitoncrosssection7">b0L-best</a> <a href="79165?version=1&table=Limitoncrosssection8">b0L-SRA350</a> <a href="79165?version=1&table=Limitoncrosssection9">b0L-SRA450</a> <a href="79165?version=1&table=Limitoncrosssection10">b0L-SRB</a> <a href="79165?version=1&table=Limitoncrosssection11">b1L-best</a> <a href="79165?version=1&table=Limitoncrosssection12">b1L-SRA300-2j</a> <a href="79165?version=1&table=Limitoncrosssection13">b1L-SRA450</a> <a href="79165?version=1&table=Limitoncrosssection14">b1L-SRA600</a> <a href="79165?version=1&table=Limitoncrosssection15">b1L-SRA750</a> <a href="79165?version=1&table=Limitoncrosssection16">b1L-SRB</a> <a href="79165?version=1&table=Limitoncrosssection17">best combination</a> <a href="79165?version=1&table=Limitoncrosssection18">A-LowMass</a> <a href="79165?version=1&table=Limitoncrosssection19">A-HighMass</a> <a href="79165?version=1&table=Limitoncrosssection20">B combination</a><br/><br/><b>Cutflow:</b><br/><i>symmetric:</i> <a href="79165?version=1&table=CutflowTable1">b0L-SRA (1 TeV, 1 GeV)</a> <a href="79165?version=1&table=CutflowTable2">b0L-SRB (700 GeV, 450 GeV)</a> <a href="79165?version=1&table=CutflowTable3">b0L-SRC (450 GeV, 430 GeV)</a><br/><i>mixed:</i> <a href="79165?version=1&table=CutflowTable4">b1L-SRA (700 GeV, 300 GeV)</a> <a href="79165?version=1&table=CutflowTable5">b1L-SRA300-2j (700 GeV, 300 GeV)</a> <a href="79165?version=1&table=CutflowTable6">b0L-SRA (700 GeV, 300 GeV)</a><br/><br/><b>Truth Code</b> and <b>SLHA Files</b> for the cutflows are available under "Resources" (purple button on the left)
- - - - - - - - - - - - - - - - - - - - <br/><b>Acceptance:</b><br/><i>symmetric:</i> <a href="79165?version=1&table=Acceptance1">b0L-SRA350</a> <a href="79165?version=1&table=Acceptance2">b0L-SRA450</a> <a href="79165?version=1&table=Acceptance3">b0L-SRA550</a> <a href="79165?version=1&table=Acceptance4">b0L-SRB</a> <a href="79165?version=1&table=Acceptance5">b0L-SRC</a> <a href="79165?version=1&table=Acceptance6">b0L-best</a><br/><i>asymmetric:</i> <a href="79165?version=1&table=Acceptance7">b1L-SRA300-2j</a> <a href="79165?version=1&table=Acceptance8">b1L-SRA450</a> <a href="79165?version=1&table=Acceptance9">b1L-SRA600</a> <a href="79165?version=1&table=Acceptance10">b1L-SRA750</a> <a href="79165?version=1&table=Acceptance11">b1L-SRB</a> <a href="79165?version=1&table=Acceptance12">b1L-best</a><br/><br/><b>Efficiency:</b><br/><i>symmetric:</i> <a href="79165?version=1&table=Efficiency1">b0L-SRA350</a> <a href="79165?version=1&table=Efficiency2">b0L-SRA450</a> <a href="79165?version=1&table=Efficiency3">b0L-SRA550</a> <a href="79165?version=1&table=Efficiency4">b0L-SRB</a> <a href="79165?version=1&table=Efficiency5">b0L-SRC</a> <a href="79165?version=1&table=Efficiency6">b0L-best</a><br/><i>asymmetric:</i> <a href="79165?version=1&table=Efficiency7">b1L-SRA300-2j</a> <a href="79165?version=1&table=Efficiency8">b1L-SRA450</a> <a href="79165?version=1&table=Efficiency9">b1L-SRA600</a> <a href="79165?version=1&table=Efficiency10">b1L-SRA750</a> <a href="79165?version=1&table=Efficiency11">b1L-SRB</a> <a href="79165?version=1&table=Efficiency12">b1L-best</a><br/><br/><b>Best SR Mapping:</b><br/><i>symmetric:</i> <a href="79165?version=1&table=BestSR4">b0L</a><br/><i>asymmetric:</i> <a href="79165?version=1&table=BestSR1">b1L</a> <a href="79165?version=1&table=BestSR2">b0L</a> <a href="79165?version=1&table=BestSR3">combined</a><br/><br/><b>Exclusion Contour:</b><br/><i>symmetric:</i> b0L-SRA350 <a href="79165?version=1&table=Contour1">exp</a> <a href="79165?version=1&table=Contour2">obs</a> b0L-SRA450 <a href="79165?version=1&table=Contour5">exp</a> <a href="79165?version=1&table=Contour6">obs</a> b0L-SRA550 <a href="79165?version=1&table=Contour9">exp</a> <a href="79165?version=1&table=Contour10">obs</a> b0L-SRB <a href="79165?version=1&table=Contour11">exp</a> <a href="79165?version=1&table=Contour12">obs</a> b0L-SRC <a href="79165?version=1&table=Contour15">exp</a> <a href="79165?version=1&table=Contour16">obs</a> b0L-best <a href="79165?version=1&table=Contour17">exp</a> <a href="79165?version=1&table=Contour18">obs</a><br/><i>asymmetric:</i> b0L-SRA350 <a href="79165?version=1&table=Contour3">exp</a> <a href="79165?version=1&table=Contour4">obs</a> b0L-SRA450 <a href="79165?version=1&table=Contour7">exp</a> <a href="79165?version=1&table=Contour8">obs</a> b0L-SRB <a href="79165?version=1&table=Contour13">exp</a> <a href="79165?version=1&table=Contour14">obs</a> b0L-best <a href="79165?version=1&table=Contour19">exp</a> <a href="79165?version=1&table=Contour20">obs</a> b1L-SRA300-2j <a href="79165?version=1&table=Contour21">exp</a> <a href="79165?version=1&table=Contour22">obs</a> b1L-SRA450 <a href="79165?version=1&table=Contour23">exp</a> <a href="79165?version=1&table=Contour24">obs</a> b1L-SRA600 <a href="79165?version=1&table=Contour25">exp</a> <a href="79165?version=1&table=Contour26">obs</a> b1L-SRA750 <a href="79165?version=1&table=Contour27">exp</a> <a href="79165?version=1&table=Contour28">obs</a> b1L-SRB <a href="79165?version=1&table=Contour29">exp</a> <a href="79165?version=1&table=Contour30">obs</a> b1L-best <a href="79165?version=1&table=Contour31">exp</a> <a href="79165?version=1&table=Contour32">obs</a> A-LowMass <a href="79165?version=1&table=Contour33">exp</a> <a href="79165?version=1&table=Contour34">obs</a> A-HighMass <a href="79165?version=1&table=Contour35">exp</a> <a href="79165?version=1&table=Contour36">obs</a> B combination <a href="79165?version=1&table=Contour37">exp</a> <a href="79165?version=1&table=Contour38">obs</a> Best combination <a href="79165?version=1&table=Contour39">exp</a> <a href="79165?version=1&table=Contour40">obs</a><br/><br/><b>SR Distribution:</b><br/><a href="79165?version=1&table=SRdistribution1">b0L-SRA</a>: $m_{\mathrm{CT}}$ <a href="79165?version=1&table=SRdistribution2">b0L-SRB</a>: $\mathrm{min[m_{T}(jet_{1-4}, E_{T}^{miss})]}$ <a href="79165?version=1&table=SRdistribution3">b0L-SRC</a>: ${\cal A}$ <a href="79165?version=1&table=SRdistribution4">b1L-SRA300-2j</a>: $\mathrm{m_{bb}}$ <a href="79165?version=1&table=SRdistribution5">b1L-SRA</a>: $\mathrm{m_{eff}}$ <a href="79165?version=1&table=SRdistribution6">b1L-SRB</a>: $\mathrm{m_{T}}$<br/><br/><b>Cross section upper limit:</b><br/><i>symmetric:</i> <a href="79165?version=1&table=Limitoncrosssection1">b0L-best</a> <a href="79165?version=1&table=Limitoncrosssection2">b0L-SRA350</a> <a href="79165?version=1&table=Limitoncrosssection3">b0L-SRA450</a> <a href="79165?version=1&table=Limitoncrosssection4">b0L-SRA550</a> <a href="79165?version=1&table=Limitoncrosssection5">b0L-SRB</a> <a href="79165?version=1&table=Limitoncrosssection6">b0L-SRC</a><br/><i>asymmetric:</i> <a href="79165?version=1&table=Limitoncrosssection7">b0L-best</a> <a href="79165?version=1&table=Limitoncrosssection8">b0L-SRA350</a> <a href="79165?version=1&table=Limitoncrosssection9">b0L-SRA450</a> <a href="79165?version=1&table=Limitoncrosssection10">b0L-SRB</a> <a href="79165?version=1&table=Limitoncrosssection11">b1L-best</a> <a href="79165?version=1&table=Limitoncrosssection12">b1L-SRA300-2j</a> <a href="79165?version=1&table=Limitoncrosssection13">b1L-SRA450</a> <a href="79165?version=1&table=Limitoncrosssection14">b1L-SRA600</a> <a href="79165?version=1&table=Limitoncrosssection15">b1L-SRA750</a> <a href="79165?version=1&table=Limitoncrosssection16">b1L-SRB</a> <a href="79165?version=1&table=Limitoncrosssection17">best combination</a> <a href="79165?version=1&table=Limitoncrosssection18">A-LowMass</a> <a href="79165?version=1&table=Limitoncrosssection19">A-HighMass</a> <a href="79165?version=1&table=Limitoncrosssection20">B combination</a><br/><br/><b>Cutflow:</b><br/><i>symmetric:</i> <a href="79165?version=1&table=CutflowTable1">b0L-SRA (1 TeV, 1 GeV)</a> <a href="79165?version=1&table=CutflowTable2">b0L-SRB (700 GeV, 450 GeV)</a> <a href="79165?version=1&table=CutflowTable3">b0L-SRC (450 GeV, 430 GeV)</a><br/><i>mixed:</i> <a href="79165?version=1&table=CutflowTable4">b1L-SRA (700 GeV, 300 GeV)</a> <a href="79165?version=1&table=CutflowTable5">b1L-SRA300-2j (700 GeV, 300 GeV)</a> <a href="79165?version=1&table=CutflowTable6">b0L-SRA (700 GeV, 300 GeV)</a><br/><br/><b>Truth Code</b> and <b>SLHA Files</b> for the cutflows are available under "Resources" (purple button on the left)
Signal acceptance (in %) in the ( M(SBOTTOM), M(NEUTRALINO) ) mass plane for the symmetric decay of the sbottom into bottom quark and neutralino, for the b0L-SRA350 signal region.
A search for massive coloured resonances which are pair-produced and decay into two jets is presented. The analysis uses 36.7 fb$^{-1}$ of $\sqrt{s}=$ 13 TeV pp collision data recorded by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the background prediction is observed. Results are interpreted in a SUSY simplified model where the lightest supersymmetric particle is the top squark, $\tilde{t}$, which decays promptly into two quarks through $R$-parity-violating couplings. Top squarks with masses in the range 100 GeV < $m_{\tilde{t}}$ < 410 GeV are excluded at 95% confidence level. If the decay is into a $b$-quark and a light quark, a dedicated selection requiring two $b$-tags is used to exclude masses in the ranges 100 GeV < $m_{\tilde{t}}$ < 470 GeV and 480 GeV < $m_{\tilde{t}}$ < 610 GeV. Additional limits are set on the pair-production of massive colour-octet resonances.
- - - - - - - - - - - - - - - - - - - - <p><b>Cutflows:</b><br> <a href="79059?version=1&table=CutflowTable1">Stop 100GeV</a><br> <a href="79059?version=1&table=CutflowTable2">Stop 500GeV</a><br> <a href="79059?version=1&table=CutflowTable3">Coloron 1500GeV</a><br> </p> <p><b>Event Yields:</b><br> <a href="79059?version=1&table=SRdistribution1">Inclusive stop SR</a><br> <a href="79059?version=1&table=SRdistribution2">Inclusive coloron SR </a><br> <a href="79059?version=1&table=SRdistribution3">b-tagged stop SR</a><br> </p> <p><b>Acceptances and Efficiencies:</b><br> <a href="79059?version=1&table=Acceptance1">Inclusive stop SR, before mass window</a><br> <a href="79059?version=1&table=Acceptance2">Inclusive stop SR, after mass window</a><br> <a href="79059?version=1&table=Acceptance3">Inclusive coloron SR, before mass window</a><br> <a href="79059?version=1&table=Acceptance4">Inclusive coloron SR, after mass window</a><br> <a href="79059?version=1&table=Acceptance5">b-tagged stop SR, before mass window</a><br> <a href="79059?version=1&table=Acceptance6">b-tagged stop SR, after mass window</a><br> </p> <p><b>Cross section upper limits:</b><br> <a href="79059?version=1&table=Limitoncrosssection1">Inclusive stop SR</a><br> <a href="79059?version=1&table=Limitoncrosssection2">Inclusive coloron SR</a><br> <a href="79059?version=1&table=Limitoncrosssection3">b-tagged stop SR</a><br> </p> <p><b>Truth Code</b> and <b>SLHA Files</b> for the cutflows are available under "Resources" (purple button on the left) </p>
Cutflow table for a pair produced top squark of 100 GeV decaying into a b- and an s-quark.
Cutflow table for a pair produced top squark of 500 GeV decaying into a b- and an s-quark.
Results from a search for supersymmetry in events with four or more charged leptons (electrons, muons and taus) are presented. The analysis uses a data sample corresponding to 36.1 fb$^{-1}$ of proton-proton collisions delivered by the Large Hadron Collider at $\sqrt{s}=13$ TeV and recorded by the ATLAS detector. Four-lepton signal regions with up to two hadronically decaying taus are designed to target a range of supersymmetric scenarios that can be either enriched in or depleted of events involving the production and decay of a $Z$ boson. Data yields are consistent with Standard Model expectations and results are used to set upper limits on the event yields from processes beyond the Standard Model. Exclusion limits are set at the 95% confidence level in simplified models of General Gauge Mediated supersymmetry, where higgsino masses are excluded up to 295 GeV. In $R$-parity-violating simplified models with decays of the lightest supersymmetric particle to charged leptons, lower limits of 1.46 TeV, 1.06 TeV, and 2.25 TeV are placed on wino, slepton and gluino masses, respectively.
The $m_{\mathrm{eff}}$ distribution for events passing the signal region requirements except the $m_{\mathrm{eff}}$ requirement in SR0A and SR0B. Distributions for data, the estimated SM backgrounds, and an example SUSY scenario are shown. "Other" is the sum of the $tWZ$, $t\bar{t}WW$, and $t\bar{t}t\bar{t}$ backgrounds. The last bin captures the overflow events. Both the statistical and systematic uncertainties in the SM background are included in the shaded band. The red arrows indicate the $m_{\mathrm{eff}}$ selections in the signal regions.
The $E_{\mathrm{T}}^{\mathrm{miss}}$ distribution for events passing the signal region requirements except the $E_{\mathrm{T}}^{\mathrm{miss}}$ requirement in SR0C and SR0D. Distributions for data, the estimated SM backgrounds, and an example SUSY scenario are shown. "Other" is the sum of the $tWZ$, $t\bar{t}WW$, and $t\bar{t}t\bar{t}$ backgrounds. The last bin captures the overflow events. Both the statistical and systematic uncertainties in the SM background are included in the shaded band. The red arrows indicate the $E_{\mathrm{T}}^{\mathrm{miss}}$ selections in the signal regions.
The $m_{\mathrm{eff}}$ distribution for events passing the signal region requirements except the $m_{\mathrm{eff}}$ requirement in SR1. Distributions for data, the estimated SM backgrounds, and an example SUSY scenario are shown. "Other" is the sum of the $tWZ$, $t\bar{t}WW$, and $t\bar{t}t\bar{t}$ backgrounds. The last bin captures the overflow events. Both the statistical and systematic uncertainties in the SM background are included in the shaded band. The red arrows indicate the $m_{\mathrm{eff}}$ selections in the signal region.
A search is presented for the direct pair production of the stop, the supersymmetric partner of the top quark, that decays through an $R$-parity-violating coupling to a final state with two leptons and two jets, at least one of which is identified as a $b$-jet. The dataset corresponds to an integrated luminosity of 36.1 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of $\sqrt{s} = 13$ TeV, collected in 2015 and 2016 by the ATLAS detector at the LHC. No significant excess is observed over the Standard Model background, and exclusion limits are set on stop pair production at a 95% confidence level. Lower limits on the stop mass are set between 600 GeV and 1.5 TeV for branching ratios above 10% for decays to an electron or muon and a $b$-quark.
Signal acceptance (in %) in the (BRe,BRtau) plane for a 800 GeV stop, for the SR800 signal region.
Expected exclusion limit contour in the (BRe,BRtau) plane for a 600 GeV stop. All limits are computed at 95% CL.
Expected exclusion limit contour in the (BRe,BRtau) plane for a 600 GeV stop. All limits are computed at 95% CL.
A search for pair production of the supersymmetric partners of the Higgs boson (higgsinos $\tilde{H}$) in gauge-mediated scenarios is reported. Each higgsino is assumed to decay to a Higgs boson and a gravitino. Two complementary analyses, targeting high- and low-mass signals, are performed to maximize sensitivity. The two analyses utilize LHC $pp$ collision data at a center-of-mass energy $\sqrt{s} = 13$ TeV, the former with an integrated luminosity of 36.1 fb$^{-1}$ and the latter with 24.3 fb$^{-1}$, collected with the ATLAS detector in 2015 and 2016. The search is performed in events containing missing transverse momentum and several energetic jets, at least three of which must be identified as $b$-quark jets. No significant excess is found above the predicted background. Limits on the cross-section are set as a function of the mass of the $\tilde{H}$ in simplified models assuming production via mass-degenerate higgsinos decaying to a Higgs boson and a gravitino. Higgsinos with masses between 130 and 230 GeV and between 290 and 880 GeV are excluded at the 95% confidence level. Interpretations of the limits in terms of the branching ratio of the higgsino to a $Z$ boson or a Higgs boson are also presented, and a 45% branching ratio to a Higgs boson is excluded for $m_{\tilde{H}} \approx 400$ GeV.
Distribution of m(h1) for events passing the preselection criteria of the high-mass analysis.
Distribution of effective mass for events passing the preselection criteria of the high-mass analysis.
Exclusion limits on higgsino pair production. The results of the low-mass analysis are used below m(higgsino) = 300 GeV, while those of the high-mass analysis are used above. The figure shows the observed and expected 95% upper limits on the higgsino pair production cross-section as a function of m(higgsino).
A search for long-lived, massive particles predicted by many theories beyond the Standard Model is presented. The search targets final states with large missing transverse momentum and at least one high-mass displaced vertex with five or more tracks, and uses 32.8 fb$^{-1}$ of $\sqrt{s}$ = 13 TeV $pp$ collision data collected by the ATLAS detector at the LHC. The observed yield is consistent with the expected background. The results are used to extract 95\% CL exclusion limits on the production of long-lived gluinos with masses up to 2.37 TeV and lifetimes of $\mathcal{O}(10^{-2})$-$\mathcal{O}(10)$ ns in a simplified model inspired by Split Supersymmetry.
Vertex reconstruction efficiency as a function of radial position $R$ with and without the special LRT processing for one $R$-hadron signal sample with $m_{\tilde{g}} = 1.2$ TeV, $m_{\tilde{\chi}_{1}^{0}} = 100$ GeV and $\tau_{\tilde{g}} = 1$ ns. The efficiency is defined as the probability for a true LLP decay to be matched with a reconstructed DV fulfilling the vertex preselection criteria in events with a reconstructed primary vertex.
Vertex reconstruction efficiency as a function of radial position $R$ for two $R$-hadron signal samples with $m_{\tilde{g}} = 1.2$ TeV, $\tau_{\tilde{g}} = 1$ ns and different neutralino masses. The efficiency is defined as the probability for a true LLP decay to be matched with a reconstructed DV fulfilling the vertex preselection criteria in events with a reconstructed primary vertex.
Fractions of selected events for several signal MC samples with a gluino lifetime $\tau = 1$ ns, illustrating how $\mathcal{A}\times\varepsilon$ varies with the model parameters.
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