We present a search for magnetic monopoles and high-electric-charge objects using LHC Run 2 $\sqrt{s} =$13 TeV proton$-$proton collisions recorded by the ATLAS detector. A total integrated luminosity of 138 fb$^{-1}$ was collected by a specialized trigger. No highly ionizing particle candidate was observed. Considering the Drell-Yan and photon-fusion pair production mechanisms as benchmark models, cross-section upper limits are presented for spin-0 and spin-$\frac{1}{2}$ magnetic monopoles of magnetic charge $1g_\textrm{D}$ and $2g_\textrm{D}$ and for high-electric-charge objects of electric charge $20 \leq |z| \leq 100$, for masses between 200 GeV and 4000 GeV. The search improves by approximately a factor of three the previous cross-section limits on the Drell-Yan production of magnetic monopoles and high-electric charge objects. Also, the first ATLAS limits on the photon-fusion pair production mechanism of magnetic monopoles and high-electric-charge objects have been obtained.
Selection efficiency as a function of transverse kinetic energy $E^\text{kin}_\text{T}=E_\text{kin}\sin\theta$ and pseudorapidity $|\eta|$ for $g=2g_\textrm{D}$ monopoles of mass 2500 GeV.
New particles with large masses that decay into hadronically interacting particles are predicted by many models of physics beyond the Standard Model. A search for a massive resonance that decays into pairs of dijet resonances is performed using 140 fb$^{-1}$ of proton$-$proton collisions at $\sqrt{s}=13$ TeV recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. Resonances are searched for in the invariant mass of the tetrajet system, and in the average invariant mass of the pair of dijet systems. A data-driven background estimate is obtained by fitting the tetrajet and dijet invariant mass distributions with a four-parameter dijet function and a search for local excesses from resonant production of dijet pairs is performed. No significant excess of events beyond the Standard Model expectation is observed, and upper limits are set on the production cross-sections of new physics scenarios.
The average dijet invariant mass distributions in data, along with the fitted background estimates for 0.28 < $\alpha$ < 0.30.
A search is presented for displaced production of Higgs bosons or $Z$ bosons, originating from the decay of a neutral long-lived particle (LLP) and reconstructed in the decay modes $H\rightarrow \gamma\gamma$ and $Z\rightarrow ee$. The analysis uses the full Run 2 data set of proton$-$proton collisions delivered by the LHC at an energy of $\sqrt{s}=13$ TeV between 2015 and 2018 and recorded by the ATLAS detector, corresponding to an integrated luminosity of 139 fb$^{-1}$. Exploiting the capabilities of the ATLAS liquid argon calorimeter to precisely measure the arrival times and trajectories of electromagnetic objects, the analysis searches for the signature of pairs of photons or electrons which arise from a common displaced vertex and which arrive after some delay at the calorimeter. The results are interpreted in a gauge-mediated supersymmetry breaking model with pair-produced higgsinos that decay to LLPs, and each LLP subsequently decays into either a Higgs boson or a $Z$ boson. The final state includes at least two particles that escape direct detection, giving rise to missing transverse momentum. No significant excess is observed above the background expectation. The results are used to set upper limits on the cross section for higgsino pair production, up to a $\tilde\chi^0_1$ mass of 369 (704) GeV for decays with 100% branching ratio of $\tilde\chi^0_1$ to Higgs ($Z$) bosons for a $\tilde\chi^0_1$ lifetime of 2 ns. A model-independent limit is also set on the production of pairs of photons or electrons with a significant delay in arrival at the calorimeter.
The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ branching ratio to the SM Higgs boson, where the assumed cross-section is for higgsino production, and $\mathcal{B}$($\tilde\chi^0_1$ $\rightarrow Z +\tilde{G}$) = 1 - $\mathcal{B}$($\tilde\chi^0_1$ $\rightarrow H + \tilde{G}$). Several signal hypotheses are overlaid that are labelled by the $\tilde\chi^0_1$ mass, all with a fixed $\tilde\chi^0_1$ lifetime of 2 ns.
A search for long-lived particles decaying into hadrons is presented. The analysis uses 139 fb$^{-1}$ of $pp$ collision data collected at $\sqrt{s} = 13$ TeV by the ATLAS detector at the LHC using events that contain multiple energetic jets and a displaced vertex. The search employs dedicated reconstruction techniques that significantly increase the sensitivity to long-lived particles decaying in the ATLAS inner detector. Background estimates for Standard Model processes and instrumental effects are extracted from data. The observed event yields are compatible with those expected from background processes. The results are used to set limits at 95% confidence level on model-independent cross sections for processes beyond the Standard Model, and on scenarios with pair-production of supersymmetric particles with long-lived electroweakinos that decay via a small $R$-parity-violating coupling. The pair-production of electroweakinos with masses below 1.5 TeV is excluded for mean proper lifetimes in the range from 0.03 ns to 1 ns. When produced in the decay of $m(\tilde{g})=2.4$ TeV gluinos, electroweakinos with $m(\tilde\chi^0_1)=1.5$ TeV are excluded with lifetimes in the range of 0.02 ns to 4 ns.
<b>Tables of Yields:</b> <a href="?table=validation_regions_yields_highpt_SR">Validation Regions Summary Yields, High-pT jet selections</a> <a href="?table=validation_regions_yields_trackless_SR">Validiation Regions Summary Yields, Trackless jet selections</a> <a href="?table=yields_highpt_SR_observed">Signal region (and sidebands) observed yields, High-pT jet selections</a> <a href="?table=yields_highpt_SR_expected">Signal region (and sidebands) expected yields, High-pT jet selections</a> <a href="?table=yields_trackless_SR_observed">Signal region (and sidebands) observed yields, Trackless jet selections</a> <a href="?table=yields_trackless_SR_expected">Signal region (and sidebands) expected yields, Trackless jet selections</a> <b>Exclusion Contours:</b> <a href="?table=excl_ewk_exp_nominal">EWK RPV signal; expected, nominal</a> <a href="?table=excl_ewk_exp_up">EWK RPV signal; expected, $+1\sigma$</a> <a href="?table=excl_ewk_exp_down">EWK RPV signal; expected, $-1\sigma$</a> <a href="?table=excl_ewk_obs_nominal">EWK RPV signal; observed, nominal</a> <a href="?table=excl_ewk_obs_up">EWK RPV signal; observed, $+1\sigma$</a> <a href="?table=excl_ewk_obs_down">EWK RPV signal; observed, $-1\sigma$</a> <a href="?table=excl_strong_mgluino_2400_GeV_exp_nominal">Strong RPV signal, m($\tilde{g}$)=2.4 TeV; expected, nominal</a> <a href="?table=excl_strong_mgluino_2400_GeV_exp_up">Strong RPV signal, m($\tilde{g}$)=2.4 TeV; expected, $+1\sigma$</a> <a href="?table=excl_strong_mgluino_2400_GeV_exp_down">Strong RPV signal, m($\tilde{g}$)=2.4 TeV; expected, $-1\sigma$</a> <a href="?table=excl_strong_mgluino_2400_GeV_obs_nominal">Strong RPV signal, m($\tilde{g}$)=2.4 TeV; observed, nominal</a> <a href="?table=excl_strong_mgluino_2400_GeV_obs_up">Strong RPV signal, m($\tilde{g}$)=2.4 TeV; observed, $+1\sigma$</a> <a href="?table=excl_strong_mgluino_2400_GeV_obs_down">Strong RPV signal, m($\tilde{g}$)=2.4 TeV; observed, $-1\sigma$</a> <a href="?table=excl_xsec_ewk">EWK RPV signal; cross-section limits for fixed lifetime values.</a> <a href="?table=excl_xsec_strong_mgluino_2400">Strong RPV signal, m($\tilde{g}$)=2.4 TeV; cross-section limits for fixed lifetime values.</a> <a href="?table=excl_strong_mgluino_2000_GeV_exp_nominal">Strong RPV signal, m($\tilde{g}$)=2.0 TeV; expected, nominal</a> <a href="?table=excl_strong_mgluino_2000_GeV_exp_up">Strong RPV signal, m($\tilde{g}$)=2.0 TeV; expected, $+1\sigma$</a> <a href="?table=excl_strong_mgluino_2000_GeV_exp_down">Strong RPV signal, m($\tilde{g}$)=2.0 TeV; expected, $-1\sigma$</a> <a href="?table=excl_strong_mgluino_2000_GeV_obs_nominal">Strong RPV signal, m($\tilde{g}$)=2.0 TeV; observed, nominal</a> <a href="?table=excl_strong_mgluino_2000_GeV_obs_up">Strong RPV signal, m($\tilde{g}$)=2.0 TeV; observed, $+1\sigma$</a> <a href="?table=excl_strong_mgluino_2000_GeV_obs_down">Strong RPV signal, m($\tilde{g}$)=2.0 TeV; observed, $-1\sigma$</a> <a href="?table=excl_strong_mgluino_2200_GeV_exp_nominal">Strong RPV signal, m($\tilde{g}$)=2.2 TeV; expected, nominal</a> <a href="?table=excl_strong_mgluino_2200_GeV_exp_up">Strong RPV signal, m($\tilde{g}$)=2.2 TeV; expected, $+1\sigma$</a> <a href="?table=excl_strong_mgluino_2200_GeV_exp_down">Strong RPV signal, m($\tilde{g}$)=2.2 TeV; expected, $-1\sigma$</a> <a href="?table=excl_strong_mgluino_2200_GeV_obs_nominal">Strong RPV signal, m($\tilde{g}$)=2.2 TeV; observed, nominal</a> <a href="?table=excl_strong_mgluino_2200_GeV_obs_up">Strong RPV signal, m($\tilde{g}$)=2.2 TeV; observed, $+1\sigma$</a> <a href="?table=excl_strong_mgluino_2200_GeV_obs_down">Strong RPV signal, m($\tilde{g}$)=2.2 TeV; observed, $-1\sigma$</a> <a href="?table=excl_strong_mchi0_50_GeV_exp_nominal">Strong RPV signal, m($\tilde{\chi}^{0}$)=0.1 TeV; expected, nominal</a> <a href="?table=excl_strong_mchi0_50_GeV_exp_up">Strong RPV signal, m($\tilde{\chi}^{0}$)=0.1 TeV; expected, $+1\sigma$</a> <a href="?table=excl_strong_mchi0_50_GeV_exp_down">Strong RPV signal, m($\tilde{\chi}^{0}$)=0.1 TeV; expected, $-1\sigma$</a> <a href="?table=excl_strong_mchi0_50_GeV_obs_nominal">Strong RPV signal, m($\tilde{\chi}^{0}$)=0.1 TeV; observed, nominal</a> <a href="?table=excl_strong_mchi0_50_GeV_obs_up">Strong RPV signal, m($\tilde{\chi}^{0}$)=0.1 TeV; observed, $+1\sigma$</a> <a href="?table=excl_strong_mchi0_50_GeV_obs_down">Strong RPV signal, m($\tilde{\chi}^{0}$)=0.1 TeV; observed, $-1\sigma$</a> <a href="?table=excl_strong_mchi0_450_GeV_exp_nominal">Strong RPV signal, m($\tilde{\chi}^{0}$)=0.5 TeV; expected, nominal</a> <a href="?table=excl_strong_mchi0_450_GeV_exp_up">Strong RPV signal, m($\tilde{\chi}^{0}$)=0.5 TeV; expected, $+1\sigma$</a> <a href="?table=excl_strong_mchi0_450_GeV_exp_down">Strong RPV signal, m($\tilde{\chi}^{0}$)=0.5 TeV; expected, $-1\sigma$</a> <a href="?table=excl_strong_mchi0_450_GeV_obs_nominal">Strong RPV signal, m($\tilde{\chi}^{0}$)=0.5 TeV; observed, nominal</a> <a href="?table=excl_strong_mchi0_450_GeV_obs_up">Strong RPV signal, m($\tilde{\chi}^{0}$)=0.5 TeV; observed, $+1\sigma$</a> <a href="?table=excl_strong_mchi0_450_GeV_obs_down">Strong RPV signal, m($\tilde{\chi}^{0}$)=0.5 TeV; observed, $-1\sigma$</a> <a href="?table=excl_strong_tau_0p01_ns_exp_nominal">Strong RPV signal, $\tau$=0.01 ns; expected, nominal</a> <a href="?table=excl_strong_tau_0p01_ns_exp_up">Strong RPV signal, $\tau$=0.01 ns; expected, $+1\sigma$</a> <a href="?table=excl_strong_tau_0p01_ns_exp_down">Strong RPV signal, $\tau$=0.01 ns; expected, $-1\sigma$</a> <a href="?table=excl_strong_tau_0p01_ns_obs_nominal">Strong RPV signal, $\tau$=0.01 ns; observed, nominal</a> <a href="?table=excl_strong_tau_0p01_ns_obs_up">Strong RPV signal, $\tau$=0.01 ns; observed, $+1\sigma$</a> <a href="?table=excl_strong_tau_0p01_ns_obs_down">Strong RPV signal, $\tau$=0.01 ns; observed, $-1\sigma$</a> <a href="?table=excl_strong_tau_0p1_ns_exp_nominal">Strong RPV signal, $\tau$=0.10 ns; expected, nominal</a> <a href="?table=excl_strong_tau_0p1_ns_exp_up">Strong RPV signal, $\tau$=0.10 ns; expected, $+1\sigma$</a> <a href="?table=excl_strong_tau_0p1_ns_exp_down">Strong RPV signal, $\tau$=0.10 ns; expected, $-1\sigma$</a> <a href="?table=excl_strong_tau_0p1_ns_obs_nominal">Strong RPV signal, $\tau$=0.10 ns; observed, nominal</a> <a href="?table=excl_strong_tau_0p1_ns_obs_up">Strong RPV signal, $\tau$=0.10 ns; observed, $+1\sigma$</a> <a href="?table=excl_strong_tau_0p1_ns_obs_down">Strong RPV signal, $\tau$=0.10 ns; observed, $-1\sigma$</a> <a href="?table=excl_strong_tau_1_ns_exp_nominal">Strong RPV signal, $\tau$=1.00 ns; expected, nominal</a> <a href="?table=excl_strong_tau_1_ns_exp_up">Strong RPV signal, $\tau$=1.00 ns; expected, $+1\sigma$</a> <a href="?table=excl_strong_tau_1_ns_exp_down">Strong RPV signal, $\tau$=1.00 ns; expected, $-1\sigma$</a> <a href="?table=excl_strong_tau_1_ns_obs_nominal">Strong RPV signal, $\tau$=1.00 ns; observed, nominal</a> <a href="?table=excl_strong_tau_1_ns_obs_up">Strong RPV signal, $\tau$=1.00 ns; observed, $+1\sigma$</a> <a href="?table=excl_strong_tau_1_ns_obs_down">Strong RPV signal, $\tau$=1.00 ns; observed, $-1\sigma$</a> <a href="?table=excl_strong_tau_10_ns_exp_nominal">Strong RPV signal, $\tau$=10.00 ns; expected, nominal</a> <a href="?table=excl_strong_tau_10_ns_exp_up">Strong RPV signal, $\tau$=10.00 ns; expected, $+1\sigma$</a> <a href="?table=excl_strong_tau_10_ns_exp_down">Strong RPV signal, $\tau$=10.00 ns; expected, $-1\sigma$</a> <a href="?table=excl_strong_tau_10_ns_obs_nominal">Strong RPV signal, $\tau$=10.00 ns; observed, nominal</a> <a href="?table=excl_strong_tau_10_ns_obs_up">Strong RPV signal, $\tau$=10.00 ns; observed, $+1\sigma$</a> <a href="?table=excl_strong_tau_10_ns_obs_down">Strong RPV signal, $\tau$=10.00 ns; observed, $-1\sigma$</a> <a href="?table=excl_xsec_strong_chi0_1250">Strong RPV signal, m($\tilde{\chi}^0_1$)=1.25 TeV; cross-section limits for fixed lifetime values.</a> <br/><b>Reinterpretation Material:</b> See the attached resource (purple button on the left) or directly <a href="https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2016-08/hepdata_info.pdf">this link</a> for information about acceptance definition and about how to use the efficiency histograms below. SLHA files are also available in the reource page of this HEPData record. <a href="?table=acceptance_highpt_strong"> Acceptance cutflow, High-pT SR, Strong production.</a> <a href="?table=acceptance_trackless_ewk"> Acceptance cutflow, Trackless SR, EWK production.</a> <a href="?table=acceptance_trackless_ewk_hf"> Acceptance cutflow, Trackless SR, EWK production with heavy-flavor.</a> <a href="?table=acceptance_highpt_ewk_hf"> Acceptance cutflow, Trackless SR, EWK production with heavy-flavor.</a> <a href="?table=event_efficiency_HighPt_R_1150_mm">Reinterpretation Material: Event-level Efficiency for HighPt SR selections, R < 1150 mm</a> <a href="?table=event_efficiency_HighPt_R_1150_3870_mm">Reinterpretation Material: Event-level Efficiency for HighPt SR selections, R [1150, 3870] mm</a> <a href="?table=event_efficiency_HighPt_R_3870_mm">Reinterpretation Material: Event-level Efficiency for HighPt SR selections, R > 3870 mm</a> <a href="?table=event_efficiency_Trackless_R_1150_mm">Reinterpretation Material: Event-level Efficiency for Trackless SR selections, R < 1150 mm</a> <a href="?table=event_efficiency_Trackless_R_1150_3870_mm">Reinterpretation Material: Event-level Efficiency for Trackless SR selections, R [1150, 3870] mm</a> <a href="?table=event_efficiency_Trackless_R_3870_mm">Reinterpretation Material: Event-level Efficiency for Trackless SR selections, R > 3870 mm</a> <a href="?table=vertex_efficiency_R_22_mm">Reinterpretation Material: Vertex-level Efficiency for R < 22 mm</a> <a href="?table=vertex_efficiency_R_22_25_mm">Reinterpretation Material: Vertex-level Efficiency for R [22, 25] mm</a> <a href="?table=vertex_efficiency_R_25_29_mm">Reinterpretation Material: Vertex-level Efficiency for R [25, 29] mm</a> <a href="?table=vertex_efficiency_R_29_38_mm">Reinterpretation Material: Vertex-level Efficiency for R [29, 38] mm</a> <a href="?table=vertex_efficiency_R_38_46_mm">Reinterpretation Material: Vertex-level Efficiency for R [38, 46] mm</a> <a href="?table=vertex_efficiency_R_46_73_mm">Reinterpretation Material: Vertex-level Efficiency for R [46, 73] mm</a> <a href="?table=vertex_efficiency_R_73_84_mm">Reinterpretation Material: Vertex-level Efficiency for R [73, 84] mm</a> <a href="?table=vertex_efficiency_R_84_111_mm">Reinterpretation Material: Vertex-level Efficiency for R [84, 111] mm</a> <a href="?table=vertex_efficiency_R_111_120_mm">Reinterpretation Material: Vertex-level Efficiency for R [111, 120] mm</a> <a href="?table=vertex_efficiency_R_120_145_mm">Reinterpretation Material: Vertex-level Efficiency for R [120, 145] mm</a> <a href="?table=vertex_efficiency_R_145_180_mm">Reinterpretation Material: Vertex-level Efficiency for R [145, 180] mm</a> <a href="?table=vertex_efficiency_R_180_300_mm">Reinterpretation Material: Vertex-level Efficiency for R [180, 300] mm</a> <br/><b>Cutflow Tables:</b> <a href="?table=cutflow_highpt_strong"> Cutflow (Acceptance x Efficiency), High-pT SR, Strong production.</a> <a href="?table=cutflow_trackless_ewk"> Cutflow (Acceptance x Efficiency), Trackless SR, EWK production.</a> <a href="?table=cutflow_trackless_ewk_hf"> Cutflow (Acceptance x Efficiency), Trackless SR, EWK production with heavy-flavor quarks.</a> <a href="?table=cutflow_highpt_ewk_hf"> Cutflow (Acceptance x Efficiency), High-pT SR, EWK production with heavy-flavor quarks.</a>
Reinterpretation Material: Vertex-level Efficiency for R < 22 mm
Reinterpretation Material: Vertex-level Efficiency for R [22, 25] mm
This paper presents a statistical combination of searches targeting final states with two top quarks and invisible particles, characterised by the presence of zero, one or two leptons, at least one jet originating from a $b$-quark and missing transverse momentum. The analyses are searches for phenomena beyond the Standard Model consistent with the direct production of dark matter in $pp$ collisions at the LHC, using 139 fb$^{-\text{1}}$ of data collected with the ATLAS detector at a centre-of-mass energy of 13 TeV. The results are interpreted in terms of simplified dark matter models with a spin-0 scalar or pseudoscalar mediator particle. In addition, the results are interpreted in terms of upper limits on the Higgs boson invisible branching ratio, where the Higgs boson is produced according to the Standard Model in association with a pair of top quarks. For scalar (pseudoscalar) dark matter models, with all couplings set to unity, the statistical combination extends the mass range excluded by the best of the individual channels by 50 (25) GeV, excluding mediator masses up to 370 GeV. In addition, the statistical combination improves the expected coupling exclusion reach by 14% (24%), assuming a scalar (pseudoscalar) mediator mass of 10 GeV. An upper limit on the Higgs boson invisible branching ratio of 0.38 (0.30$^{+\text{0.13}}_{-\text{0.09}}$) is observed (expected) at 95% confidence level.
Cutflow for the reference point DM+$tW$ $m(a, \chi) = (10, 1)$ GeV in signal region SRTX. The column labelled 'weighted' shows the event yield including all correction factors applied to simulation, and is normalised to 139 fb$^{-1}$. A notable exception concerns the 'weighted' numbers in the first and the second row, labelled 'Total' and 'Filtered', which correspond to $\mathcal{L}\cdot\sigma$ and $\mathcal{L}\cdot\sigma\cdot\epsilon$ expected, respectively. The 'Skim' selection requires the $p_{\text{T}}$ of the leading four jets to be above (80, 60, 40, 40) GeV, the missing transverse momentum $E_{\text{T}}^{\text{miss}} > 140$ GeV, the missing momentum significance $\mathcal{S} > 8$, $\Delta\phi_{\min}(\vec{p}_{\text{T,1-4}},\vec{p}_{\text{T}}^{\text{miss}}) > 0.4$ and a lepton veto. The 'Orthogonalisation' selection is defined in the main body. In total 100000 raw MC events were generated prior to the specified cuts, with the column 'Unweighted yield' collecting the numbers after each cut.
Results are presented from a search for physics beyond the standard model in proton-proton collisions at $\sqrt{s} =$ 13 TeV in channels with two Higgs bosons, each decaying via the process H $\to$$\mathrm{b\bar{b}}$, and large missing transverse momentum. The search uses a data sample corresponding to an integrated luminosity of 137 fb$^{-1}$ collected by the CMS experiment at the CERN LHC. The search is motivated by models of supersymmetry that predict the production of neutralinos, the neutral partners of the electroweak gauge and Higgs bosons. The observed event yields in the signal regions are found to be consistent with the standard model background expectations. The results are interpreted using simplified models of supersymmetry. For the electroweak production of nearly mass-degenerate higgsinos, each of whose decay chains yields a neutralino ($\tilde{\chi}^0_1$) that in turn decays to a massless goldstino and a Higgs boson, $\tilde{\chi}^0_1$ masses in the range 175 to 1025 GeV are excluded at 95% confidence level. For the strong production of gluino pairs decaying via a slightly lighter $\tilde{\chi}^0_2$ to H and a light $\tilde{\chi}^0_1$, gluino masses below 2330 GeV are excluded.
Pre-fit background covariance matrix $\sigma_{xy}$ for the 22 analysis bins, ordered as in Fig. 10.
Pre-fit background correlation matrix $\rho_{xy}$ for the 22 analysis bins, ordered as in Fig. 10.
Efficiency vs $m(\widetilde{\chi}^0_1)$ for SMS model TChiHH-G. The denominator includes all 22 signal regions, and assumes $\mathcal{B}(\mathrm{H}$-->$\mathrm{b}\overline{\mathrm{b}})=100\%$.
The associated production of a Higgs boson and a top-quark pair is measured in events characterised by the presence of one or two electrons or muons. The Higgs boson decay into a $b$-quark pair is used. The analysed data, corresponding to an integrated luminosity of 139 fb$^{-1}$, were collected in proton-proton collisions at the Large Hadron Collider between 2015 and 2018 at a centre-of-mass energy of $\sqrt{s}=13$ TeV. The measured signal strength, defined as the ratio of the measured signal yield to that predicted by the Standard Model, is $0.35^{+0.36}_{-0.34}$. This result is compatible with the Standard Model prediction and corresponds to an observed (expected) significance of 1.0 (2.7) standard deviations. The signal strength is also measured differentially in bins of the Higgs boson transverse momentum in the simplified template cross-section framework, including a bin for specially selected boosted Higgs bosons with transverse momentum above 300 GeV.
The ratios $S/B$ (black solid line, referring to the vertical axis on the left) and $S/\sqrt{B}$ (red dashed line, referring to the vertical axis on the right) for each category in the inclusive analysis in the dilepton channel (left) and in the single-lepton channels (right), where $S$ ($B$) is the number of selected signal (background) events predicted by the simulation and normalised to a luminosity of 139 fb$^{-1}$ .
The results of a search for direct pair production of top squarks and for dark matter in events with two opposite-charge leptons (electrons or muons), jets and missing transverse momentum are reported, using 139 fb$^{-1}$ of integrated luminosity from proton-proton collisions at $\sqrt{s} = 13$ TeV, collected by the ATLAS detector at the Large Hadron Collider during Run 2 (2015-2018). This search considers the pair production of top squarks and is sensitive across a wide range of mass differences between the top squark and the lightest neutralino. Additionally, spin-0 mediator dark-matter models are considered, in which the mediator is produced in association with a pair of top quarks. The mediator subsequently decays to a pair of dark-matter particles. No significant excess of events is observed above the Standard Model background, and limits are set at 95% confidence level. The results exclude top squark masses up to about 1 TeV, and masses of the lightest neutralino up to about 500 GeV. Limits on dark-matter production are set for scalar (pseudoscalar) mediator masses up to about 250 (300) GeV.
Two-body selection acceptance (a) SR-SF$^{2-body}_{[110,120)}$, (b) SR-SF1$^{2-body}_{[120,140)}$, (c) SR-SF2$^{2-body}_{[140,160)}$, (d) SR-SF3$^{2-body}_{[160,180)}$, (e) SR-SF4$^{2-body}_{[180,220)}$, (f) SR-SF5$^{2-body}_{[220,\infty)}$ for a simplified model assuming $ \tilde{t}_1$ pair production.
Two-body selection acceptance (a) SR-SF$^{2-body}_{[110,120)}$, (b) SR-SF1$^{2-body}_{[120,140)}$, (c) SR-SF2$^{2-body}_{[140,160)}$, (d) SR-SF3$^{2-body}_{[160,180)}$, (e) SR-SF4$^{2-body}_{[180,220)}$, (f) SR-SF5$^{2-body}_{[220,\infty)}$ for a simplified model assuming $ \tilde{t}_1$ pair production.
Two-body selection acceptance (a) SR-SF$^{2-body}_{[110,120)}$, (b) SR-SF1$^{2-body}_{[120,140)}$, (c) SR-SF2$^{2-body}_{[140,160)}$, (d) SR-SF3$^{2-body}_{[160,180)}$, (e) SR-SF4$^{2-body}_{[180,220)}$, (f) SR-SF5$^{2-body}_{[220,\infty)}$ for a simplified model assuming $ \tilde{t}_1$ pair production.
A search for heavy neutral Higgs bosons is performed using the LHC Run 2 data, corresponding to an integrated luminosity of 139 fb$^{-1}$ of proton-proton collisions at $\sqrt{s}=13$ TeV recorded with the ATLAS detector. The search for heavy resonances is performed over the mass range 0.2-2.5 TeV for the $\tau^+\tau^-$ decay with at least one $\tau$-lepton decaying into final states with hadrons. The data are in good agreement with the background prediction of the Standard Model. In the $M_{h}^{125}$ scenario of the Minimal Supersymmetric Standard Model, values of $\tan\beta>8$ and $\tan\beta>21$ are excluded at the 95% confidence level for neutral Higgs boson masses of 1.0 TeV and 1.5 TeV, respectively, where $\tan\beta$ is the ratio of the vacuum expectation values of the two Higgs doublets.
Expected 95% CL upper limits on the scalar boson production cross section times ditau branching fraction as a function of the scalar boson mass and the fraction of the b-associated production. The limits are calculated from a statistical combination of the 1l1tau_h and 2tau_h channels.
Expected 95% CL upper limits on the scalar boson production cross section times ditau branching fraction as a function of the scalar boson mass and the fraction of the b-associated production. The limits are calculated from a statistical combination of the 1l1tau_h and 2tau_h channels.
Expected 95% CL upper limits on the scalar boson production cross section times ditau branching fraction as a function of the scalar boson mass and the fraction of the b-associated production. The limits are calculated from a statistical combination of the 1l1tau_h and 2tau_h channels.
A search is presented for pair-production of long-lived neutral particles using 33 fb$^{-1}$ of $\sqrt{s} = 13$ TeV proton-proton collision data, collected during 2016 by the ATLAS detector at the LHC. This search focuses on a topology in which one long-lived particle decays in the ATLAS inner detector and the other decays in the muon spectrometer. Special techniques are employed to reconstruct the displaced tracks and vertices in the inner detector and in the muon spectrometer. One event is observed that passes the full event selection, which is consistent with the estimated background. Limits are placed on scalar boson propagators with masses from 125 GeV to 1000 GeV decaying into pairs of long-lived hidden-sector scalars with masses from 8 GeV to 400 GeV. The limits placed on several low-mass scalars extend previous exclusion limits in the range of proper lifetimes $c \tau$ from 5 cm to 1 m.
The impact of the IDVx selections on the selection efficiency for the MC signal sample with a $\Phi$ with a mass of 400 GeV decaying to an LLP with a mass of 50 GeV.
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