A search for pair-produced scalar and vector leptoquarks decaying into quarks and leptons of different generations is presented. It uses the full LHC Run 2 (2015-2018) data set of 139 fb$^{-1}$ collected with the ATLAS detector in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 13$ TeV. Scalar leptoquarks with charge -(1/3)e as well as scalar and vector leptoquarks with charge +(2/3)e are considered. All possible decays of the pair-produced leptoquarks into quarks of the third generation (t, b) and charged or neutral leptons of the first or second generation ($e, \mu, \nu$) with exactly one electron or muon in the final state are investigated. No significant deviations from the Standard Model expectation are observed. Upper limits on the production cross-section are provided for eight models as a function of the leptoquark mass and the branching ratio of the leptoquark into the charged or neutral lepton. In addition, lower limits on the leptoquark masses are derived for all models across a range of branching ratios. Two of these models have the goal of providing an explanation for the recent B-anomalies. In both models, a vector leptoquark decays into charged and neutral leptons of the second generation with a similar branching fraction. Lower limits of 1980 GeV and 1710 GeV are set on the leptoquark mass for these two models.
- - - - - - - - Overview of HEPData Record - - - - - - - - <br/><br/> <b>95% CL limits on the production cross-section for:</b> <ul> <li><a href="135703?version=1&table=%24LQ_u%20%5Crightarrow%20t%5Cnu%2Fb%5Cmu%24%20observed%20limits">scalar up-type LQs decaying into a top quark and a neutrino or a bottom quark and a muon (observed)</a> <li><a href="135703?version=1&table=%24LQ_u%20%5Crightarrow%20t%5Cnu%2Fb%5Cmu%24%20expected%20limits">scalar up-type LQs decaying into a top quark and a neutrino or a bottom quark and a muon (expected)</a> <li><a href="135703?version=1&table=%24LQ_u%20%5Crightarrow%20t%5Cnu%2Fbe%24%20observed%20limits">scalar up-type LQs decaying into a top quark and a neutrino or a bottom quark and an electron (observed)</a> <li><a href="135703?version=1&table=%24LQ_u%20%5Crightarrow%20t%5Cnu%2Fbe%24%20expected%20limits">scalar up-type LQs decaying into a top quark and a neutrino or a bottom quark and an electron (expected)</a> <li><a href="135703?version=1&table=%24LQ_d%20%5Crightarrow%20t%5Cmu%2Fb%5Cnu%24%20observed%20limits">scalar down-type LQs decaying into a bottom quark and a neutrino or a top quark and a muon (observed)</a> <li><a href="135703?version=1&table=%24LQ_d%20%5Crightarrow%20t%5Cmu%2Fb%5Cnu%24%20expected%20limits">scalar down-type LQs decaying into a bottom quark and a neutrino or a top quark and a muon (expected)</a> <li><a href="135703?version=1&table=%24LQ_d%20%5Crightarrow%20te%2Fb%5Cnu%24%20observed%20limits">scalar down-type LQs decaying into a bottom quark and a neutrino or a top quark and an electron (observed)</a> <li><a href="135703?version=1&table=%24LQ_d%20%5Crightarrow%20te%2Fb%5Cnu%24%20expected%20limits">scalar down-type LQs decaying into a bottom quark and a neutrino or a top quark and an electron (expected)</a> <li><a href="135703?version=1&table=%24vLQ_%7BYM%7D%20%5Crightarrow%20t%5Cnu%2Fb%5Cmu%24%20observed%20limits">vector up-type LQs in the Yang-Mills coupling scenario decaying into a top quark and a neutrino or a bottom quark and a muon (observed)</a> <li><a href="135703?version=1&table=%24vLQ_%7BYM%7D%20%5Crightarrow%20t%5Cnu%2Fb%5Cmu%24%20expected%20limits">vector up-type LQs in the Yang-Mills coupling scenario decaying into a top quark and a neutrino or a bottom quark and a muon (expected)</a> <li><a href="135703?version=1&table=%24vLQ_%7BYM%7D%20%5Crightarrow%20t%5Cnu%2Fbe%24%20observed%20limits">vector up-type LQs in the Yang-Mills coupling scenario decaying into a top quark and a neutrino or a bottom quark and an electron (observed)</a> <li><a href="135703?version=1&table=%24vLQ_%7BYM%7D%20%5Crightarrow%20t%5Cnu%2Fbe%24%20expected%20limits">vector up-type LQs in the Yang-Mills coupling scenario decaying into a top quark and a neutrino or a bottom quark and an electron (expected)</a> <li><a href="135703?version=1&table=%24vLQ_%7Bmin%7D%20%5Crightarrow%20t%5Cnu%2Fb%5Cmu%24%20observed%20limits">vector up-type LQs in the minimal coupling scenario decaying into a top quark and a neutrino or a bottom quark and a muon (observed)</a> <li><a href="135703?version=1&table=%24vLQ_%7Bmin%7D%20%5Crightarrow%20t%5Cnu%2Fb%5Cmu%24%20expected%20limits">vector up-type LQs in the minimal coupling scenario decaying into a top quark and a neutrino or a bottom quark and a muon (expected)</a> <li><a href="135703?version=1&table=%24vLQ_%7Bmin%7D%20%5Crightarrow%20t%5Cnu%2Fbe%24%20observed%20limits">vector up-type LQs in the minimal coupling scenario decaying into a top quark and a neutrino or a bottom quark and an electron (observed)</a> <li><a href="135703?version=1&table=%24vLQ_%7Bmin%7D%20%5Crightarrow%20t%5Cnu%2Fbe%24%20expected%20limits">vector up-type LQs in the minimal coupling scenario decaying into a top quark and a neutrino or a bottom quark and an electron (expected)</a> </ul> <b>Product of signal acceptance and efficiency in the training region for:</b> <ul> <li><a href="135703?version=1&table=%24LQ_u%20%5Crightarrow%20t%5Cnu%2Fb%5Cmu%24%20Acceptance%20times%20Efficiency">scalar up-type LQs decaying into top quarks and neutrinos or bottom quarks and muons</a> <li><a href="135703?version=1&table=%24LQ_u%20%5Crightarrow%20t%5Cnu%2Fbe%24%20Acceptance%20times%20Efficiency">scalar up-type LQs decaying into top quarks and neutrinos or bottom quarks and electrons</a> <li><a href="135703?version=1&table=%24LQ_d%20%5Crightarrow%20t%5Cmu%2Fb%5Cnu%24%20Acceptance%20times%20Efficiency">scalar down-type LQs decaying into bottom quarks and neutrinos or top quarks and muons</a> <li><a href="135703?version=1&table=%24LQ_d%20%5Crightarrow%20te%2Fb%5Cnu%24%20Acceptance%20times%20Efficiency">scalar down-type LQs decaying into bottom quarks and neutrinos or top quarks and electrons</a> <li><a href="135703?version=1&table=%24vLQ_%7BYM%7D%20%5Crightarrow%20t%5Cnu%2Fb%5Cmu%24%20Acceptance%20times%20Efficiency">vector up-type LQs in the Yang-Mills coupling scenario decaying into top quarks and neutrinos or bottom quarks and muons</a> <li><a href="135703?version=1&table=%24vLQ_%7BYM%7D%20%5Crightarrow%20t%5Cnu%2Fbe%24%20Acceptance%20times%20Efficiency">vector up-type LQs in the Yang-Mills coupling scenario decaying into top quarks and neutrinos or bottom quarks and electrons</a> <li><a href="135703?version=1&table=%24vLQ_%7Bmin%7D%20%5Crightarrow%20t%5Cnu%2Fb%5Cmu%24%20Acceptance%20times%20Efficiency">vector up-type LQs in the minimal coupling scenario decaying into top quarks and neutrinos or bottom quarks and muons</a> <li><a href="135703?version=1&table=%24vLQ_%7Bmin%7D%20%5Crightarrow%20t%5Cnu%2Fbe%24%20Acceptance%20times%20Efficiency">vector up-type LQs in the minimal coupling scenario decaying into top quarks and neutrinos or bottom quarks and electrons</a> </ul> <b>Cut-flow for:</b> <ul> <li><a href="135703?version=1&table=Scalar%20LQs%20cut-flow">scalar LQs</a> <li><a href="135703?version=1&table=Vector%20LQs%20cut-flow">vector LQs</a> </ul>
Observed 95% CL limits on the production cross-section for scalar up-type LQs decaying into a top quark and a neutrino or a bottom quark and a muon.
Expected 95% CL limits on the production cross-section for scalar up-type LQs decaying into a top quark and a neutrino or a bottom quark and a muon.
A measurement of single top-quark production in the s-channel is performed in proton$-$proton collisions at a centre-of-mass energy of 13 TeV with the ATLAS detector at the CERN Large Hadron Collider. The dataset corresponds to an integrated luminosity of 139 fb$^{-1}$. The analysis is performed on events with an electron or muon, missing transverse momentum and exactly two $b$-tagged jets in the final state. A discriminant based on matrix element calculations is used to separate single-top-quark s-channel events from the main background contributions, which are top-quark pair production and $W$-boson production in association with jets. The observed (expected) signal significance over the background-only hypothesis is 3.3 (3.9) standard deviations, and the measured cross-section is $\sigma=8.2^{+3.5}_{-2.9}$ pb, consistent with the Standard Model prediction of $\sigma^{\mathrm{SM}}=10.32^{+0.40}_{-0.36}$ pb.
Result of the s-channel single-top cross-section measurement, in pb. The statistical and systematic uncertainties are given, as well as the total uncertainty. The normalisation factors for the $t\bar{t}$ and $W$+jets backgrounds are also shown, with their total uncertainties.
Distribution of ${E}_{T}^{miss}$ after the fit of the multijet backgrounds, in the electron channel, in the signal region, without applying the cut on ${E}_{T}^{miss}$. Simulated events are normalised to the expected number of events given the integrated luminosity, after applying the normalisation factors obtained in the multijet fit. The last bin includes the overflow. The uncertainty band indicates the simulation's statistical uncertainty, the normalisation uncertainties for different processes ($40$ % for $W$+jets production, $30$ % for multijet background and $6$ % for top-quark processes) and the multijet background shape uncertainty in each bin, summed in quadrature. The lower panel of the figure shows the ratio of the data to the prediction.
Distribution of ${E}_{T}^{miss}$ after the fit of the multijet backgrounds, in the electron channel, in the $W$+jets VR, without applying the cut on ${E}_{T}^{miss}$. Simulated events are normalised to the expected number of events given the integrated luminosity, after applying the normalisation factors obtained in the multijet fit. The last bin includes the overflow. The uncertainty band indicates the simulation's statistical uncertainty, the normalisation uncertainties for different processes ($40$ % for $W$+jets production, $30$ % for multijet background and $6$ % for top-quark processes) and the multijet background shape uncertainty in each bin, summed in quadrature. The lower panel of the figure shows the ratio of the data to the prediction.
A search for a charged Higgs boson, $H^{\pm}$, produced in top-quark decays, $t \rightarrow H^{\pm}b$, is presented. The search targets $H^{\pm}$ decays into a bottom and a charm quark, $H^{\pm} \rightarrow cb$. The analysis focuses on a selection enriched in top-quark pair production, where one top quark decays into a leptonically decaying $W$ boson and a bottom quark, and the other top quark decays into a charged Higgs boson and a bottom quark. This topology leads to a lepton-plus-jets final state, characterised by an isolated electron or muon and at least four jets. The search exploits the high multiplicity of jets containing $b$-hadrons, and deploys a neural network classifier that uses the kinematic differences between the signal and the background. The search uses a dataset of proton-proton collisions collected at a centre-of-mass energy $\sqrt{s}=13$ TeV between 2015 and 2018 with the ATLAS detector at CERN's Large Hadron Collider, amounting to an integrated luminosity of 139 fb$^{-1}$. Observed (expected) 95% confidence-level upper limits between 0.15% (0.09%) and 0.42% (0.25%) are derived for the product of branching fractions $\mathscr{B}(t\rightarrow H^{\pm}b) \times \mathscr{B}(H^{\pm}\rightarrow cb)$ for charged Higgs boson masses between 60 and 160 GeV, assuming the SM production of the top-quark pairs.
The observed 95% CL upper limits on $\mathscr{B}=\mathscr{B}(t\rightarrow H^{\pm}b) \times \mathscr{B}(H^{\pm}\rightarrow cb)$ as a function of $m_{H^{\pm}}$ and the expectation (dashed) under the background-only hypothesis. The inner green and outer yellow shaded bands show the $\pm 1\sigma$ and $\pm 2\sigma$ uncertainties of the expected limits. The exclusion limits are presented for $m_{H^{\pm}}$ between 60 and 160 GeV with 10 GeV $m_{H^{\pm}}$ spacing and linear interpolation between adjacent mass points. Superimposed on the upper limits, the predictions from the 3HDM are shown, corresponding to three benchmark values for the parameters $X$, $Y$, and $Z$
Pre-fit event yields in each of the nine analysis regions. The $H^{\pm}$ signal yields for $m_{H^{\pm}}=130$ GeV and $m_{H^{\pm}}=70$ GeV are normalised to $\mathscr{B}_{\mathrm{ref}}=1\%$. The quoted uncertainties are the sum in quadrature of statistical and systematic uncertainties of the yields, computed taking into account correlations among processes resulting from the data-based $t\bar{t}$ correction procedure.
Post-fit yields in each of the nine analysis regions considered. The total prediction is shown after the fit to data under the signal-plus-background hypothesis assuming $H^{\pm}$ signal with $m_{H^{\pm}}=130$ GeV. The predicted yileds for the $H^{\pm}$ signal with $m_{H^{\pm}}=70$ GeV are also shown for reference. The best fit-values of $\mathscr{B}$ for $H^{\pm}$ signal with $m_{H^{\pm}}=130$ GeV and $m_{H^{\pm}}=70$ GeV are 0.16% and 0.07% respectively. The quoted uncertainties are the sum in quadrature of statistical and systematic uncertainties of the yields, computed taking into account correlations among nuisance parameters and among processes.
Studies of the correlations of the two highest transverse momentum (leading) jets in individual Pb+Pb collision events can provide information about the mechanism of jet quenching by the hot and dense matter created in such collisions. In Pb+Pb and pp collisions at $\sqrt{s_{_\text{NN}}}$ = 5.02 TeV, measurements of the leading dijet transverse momentum ($p_{\mathrm{T}}$) correlations are presented. Additionally, measurements in Pb+Pb collisions of the dijet pair nuclear modification factors projected along leading and subleading jet $p_{\mathrm{T}}$ are made. The measurements are performed using the ATLAS detector at the LHC with 260 pb$^{-1}$ of pp data collected in 2017 and 2.2 nb$^{-1}$ of Pb+Pb data collected in 2015 and 2018. An unfolding procedure is applied to the two-dimensional leading and subleading jet $p_{\mathrm{T}}$ distributions to account for experimental effects in the measurement of both jets. Results are provided for dijets with leading jet $p_{\mathrm{T}}$ greater than 100 GeV. Measurements of the dijet-yield-normalized $x_{\mathrm{J}}$ distributions in Pb+Pb collisions show an increased fraction of imbalanced jets compared to pp collisions; these measurements are in agreement with previous measurements of the same quantity at 2.76 TeV in the overlapping kinematic range. Measurements of the absolutely-normalized dijet rate in Pb+Pb and pp collisions are also presented, and show that balanced dijets are significantly more suppressed than imbalanced dijets in Pb+Pb collisions. It is observed in the measurements of the pair nuclear modification factors that the subleading jets are significantly suppressed relative to leading jets with $p_{\mathrm{T}}$ between 100 and 316 GeV for all centralities in Pb+Pb collisions.
absolutely normalized dijet cross sections from pp collisions
absolutely normalized dijet yields scaled by 1/<TAA> in 0-10% central PbPb collisions
absolutely normalized dijet yields scaled by 1/<TAA> in 10-20% central PbPb collisions
A search for new phenomena has been performed in final states with at least one isolated high-momentum photon, jets and missing transverse momentum in proton--proton collisions at a centre-of-mass energy of $\sqrt{s} = 13$ TeV. The data, collected by the ATLAS experiment at the CERN LHC, correspond to an integrated luminosity of 139 $fb^{-1}$. The experimental results are interpreted in a supersymmetric model in which pair-produced gluinos decay into neutralinos, which in turn decay into a gravitino, at least one photon, and jets. No significant deviations from the predictions of the Standard Model are observed. Upper limits are set on the visible cross section due to physics beyond the Standard Model, and lower limits are set on the masses of the gluinos and neutralinos, all at 95% confidence level. Visible cross sections greater than 0.022 fb are excluded and pair-produced gluinos with masses up to 2200 GeV are excluded for most of the NLSP masses investigated.
The observed and expected (post-fit) yields in the control and validation regions. The lower panel shows the difference in standard deviations between the observed and expected yields, considering both the systematic and statistical uncertainties on the background expectation.
Observed (points with error bars) and expected background (solid histograms) distributions for $E_{T}^{miss}$ in the signal region (a) SRL, (b) SRM and (c) SRH after the background-only fit applied to the CRs. The predicted signal distributions for the two models with a gluino mass of 2000 GeV and neutralino mass of 250 GeV (SRL), 1050 GeV (SRM) or 1950 GeV (SRH) are also shown for comparison. The uncertainties in the SM background are only statistical.
Observed (points with error bars) and expected background (solid histograms) distributions for $E_{T}^{miss}$ in the signal region (a) SRL, (b) SRM and (c) SRH after the background-only fit applied to the CRs. The predicted signal distributions for the two models with a gluino mass of 2000 GeV and neutralino mass of 250 GeV (SRL), 1050 GeV (SRM) or 1950 GeV (SRH) are also shown for comparison. The uncertainties in the SM background are only statistical.
This paper presents a search for hypothetical massive, charged, long-lived particles with the ATLAS detector at the LHC using an integrated luminosity of 139 fb$^{-1}$ of proton-proton collisions at $\sqrt{s}=13$ TeV. These particles are expected to move significantly slower than the speed of light and should be identifiable by their high transverse momenta and anomalously large specific ionisation losses, ${\mathrm{d}}E/\mathrm{d}x$. Trajectories reconstructed solely by the inner tracking system and a ${\mathrm{d}}E/\mathrm{d}x$ measurement in the pixel detector layers provide sensitivity to particles with lifetimes down to ${\cal O}(1)$$\text{ns}$ with a mass, measured using the Bethe--Bloch relation, ranging from 100 GeV to 3 TeV. Interpretations for pair-production of $R$-hadrons, charginos and staus in scenarios of supersymmetry compatible with these particles being long-lived are presented, with mass limits extending considerably beyond those from previous searches in broad ranges of lifetime.
This material aims to give people outside the ATLAS Collaboration the possibility to reinterpret the results from the search for heavy charged long-lived particles (CLLPs), using only particles from Monte Carlo event generators. The reinterpretation material is provided for signal regions SR-Inclusive_Low and SR-Inclusive_High. <ul display="inline-block"> <li>The "long" lifetime regime of mass windows is used.</li> <li>Users are guided to read Guide.pdf (available from "Resources" or "Download All" buttons) for how to use the provided materials for reinterpretation.</li> <li>The pseudo-code snippet snippet.cxx also illustrates a sketch of possible implementation.</li> </ul> <b>Signal Region (Discovery) mass distribution</b> <ul> <li><a href="?table=SR-Inclusive_Low%20mass%20distribution">SR-Inclusive_Low mass distribution</a></li> <li><a href="?table=SR-Inclusive_High%20mass%20distribution">SR-Inclusive_High mass distribution</a></li> </ul> <b>Signal Region (Discovery) $p_\text{T}, \eta, dE/dx$ distribution</b> <ul> <li><a href="?table=SR-Inclusive_Low%20pT%20distribution">SR-Inclusive_Low pT distribution</a></li> <li><a href="?table=SR-Inclusive_High%20pT%20distribution">SR-Inclusive_High pT distribution</a></li> <li><a href="?table=SR-Inclusive_Low%20$eta$%20distribution">SR-Inclusive_Low $\eta$ distribution</a></li> <li><a href="?table=SR-Inclusive_High%20$eta$%20distribution">SR-Inclusive_High $\eta$ distribution</a></li> <li><a href="?table=SR-Inclusive_Low%20dE/dx%20distribution">SR-Inclusive_Low dE/dx distribution</a></li> <li><a href="?table=SR-Inclusive_High%20dE/dx%20distribution">SR-Inclusive_High dE/dx distribution</a></li> </ul> <b>Signal Region (Limit Setting) mass distribution</b> <ul> <li><a href="?table=SR-Trk-IBL0_Low%20mass%20distribution">SR-Trk-IBL0_Low mass distribution</a></li> <li><a href="?table=SR-Mu-IBL0_Low%20mass%20distribution">SR-Mu-IBL0_Low mass distribution</a></li> <li><a href="?table=SR-Trk-IBL0_High%20mass%20distribution">SR-Trk-IBL0_High mass distribution</a></li> <li><a href="?table=SR-Mu-IBL0_High%20mass%20distribution">SR-Mu-IBL0_High mass distribution</a></li> <li><a href="?table=SR-Trk-IBL1%20mass%20distribution">SR-Trk-IBL1 mass distribution</a></li> <li><a href="?table=SR-Mu-IBL1%20mass%20distribution">SR-Mu-IBL1 mass distribution</a></li> </ul> <b>Signal Region (Limit Setting) $p_\text{T}$ distribution</b> <ul> <li><a href="?table=SR-Trk-IBL0_Low%20pT%20distribution">SR-Trk-IBL0_Low pT distribution</a></li> <li><a href="?table=SR-Mu-IBL0_Low%20pT%20distribution">SR-Mu-IBL0_Low pT distribution</a></li> <li><a href="?table=SR-Trk-IBL0_High%20pT%20distribution">SR-Trk-IBL0_High pT distribution</a></li> <li><a href="?table=SR-Mu-IBL0_High%20pT%20distribution">SR-Mu-IBL0_High pT distribution</a></li> <li><a href="?table=SR-Trk-IBL1%20pT%20distribution">SR-Trk-IBL1 pT distribution</a></li> <li><a href="?table=SR-Mu-IBL1%20pT%20distribution">SR-Mu-IBL1 pT distribution</a></li> </ul> <b>Signal Region (Limit Setting) $dE/dx$ distribution</b> <ul> <li><a href="?table=SR-Trk-IBL0_Low%20dE/dx%20distribution">SR-Trk-IBL0_Low dE/dx distribution</a></li> <li><a href="?table=SR-Mu-IBL0_Low%20dE/dx%20distribution">SR-Mu-IBL0_Low dE/dx distribution</a></li> <li><a href="?table=SR-Trk-IBL0_High%20dE/dx%20distribution">SR-Trk-IBL0_High dE/dx distribution</a></li> <li><a href="?table=SR-Mu-IBL0_High%20dE/dx%20distribution">SR-Mu-IBL0_High dE/dx distribution</a></li> <li><a href="?table=SR-Trk-IBL1%20dE/dx%20distribution">SR-Trk-IBL1 dE/dx distribution</a></li> <li><a href="?table=SR-Mu-IBL1%20dE/dx%20distribution">SR-Mu-IBL1 dE/dx distribution</a></li> </ul> <b>Discovery Signal Regions $p_{0}$ values</b> <ul> <li><a href="?table=p0-values%20and%20model-independent%20limits,%20short%20regime">p0-values and model-independent limits, short regime</a></li> <li><a href="?table=p0-values%20and%20model-independent%20limits,%20long%20regime">p0-values and model-independent limits, long regime</a></li> </ul> <b>Validation Region plots</b> <ul> <li><a href="?table=VR-LowPt-Inclusive_High%20mass%20distribution">VR-LowPt-Inclusive_High mass distribution</a></li> <li><a href="?table=VR-HiEta-Inclusive%20mass%20distribution">VR-HiEta-Inclusive mass distribution</a></li> </ul> <ul> <li><a href="?table=VR-LowPt-Trk-IBL0_Low%20mass%20distribution">VR-LowPt-Trk-IBL0_Low mass distribution</a></li> <li><a href="?table=VR-LowPt-Mu-IBL0_Low%20mass%20distribution">VR-LowPt-Mu-IBL0_Low mass distribution</a></li> <li><a href="?table=VR-LowPt-Trk-IBL0_High%20mass%20distribution">VR-LowPt-Trk-IBL0_High mass distribution</a></li> <li><a href="?table=VR-LowPt-Mu-IBL0_High%20mass%20distribution">VR-LowPt-Mu-IBL0_High mass distribution</a></li> <li><a href="?table=VR-LowPt-Trk-IBL1%20mass%20distribution">VR-LowPt-Trk-IBL1 mass distribution</a></li> <li><a href="?table=VR-LowPt-Mu-IBL1%20mass%20distribution">VR-LowPt-Mu-IBL1 mass distribution</a></li> </ul> <ul> <li><a href="?table=VR-HiEta-Trk-IBL0_Low%20mass%20distribution">VR-HiEta-Trk-IBL0_Low mass distribution</a></li> <li><a href="?table=VR-HiEta-Mu-IBL0_Low%20mass%20distribution">VR-HiEta-Mu-IBL0_Low mass distribution</a></li> <li><a href="?table=VR-HiEta-Trk-IBL0_High%20mass%20distribution">VR-HiEta-Trk-IBL0_High mass distribution</a></li> <li><a href="?table=VR-HiEta-Mu-IBL0_High%20mass%20distribution">VR-HiEta-Mu-IBL0_High mass distribution</a></li> <li><a href="?table=VR-HiEta-Trk-IBL1%20mass%20distribution">VR-HiEta-Trk-IBL1 mass distribution</a></li> <li><a href="?table=VR-HiEta-Mu-IBL1%20mass%20distribution">VR-HiEta-Mu-IBL1 mass distribution</a></li> </ul> <b>Mass vs. Lifetime limit plots</b> <ul> <li><a href="?table=Mass%20Limit%20vs.%20Lifetime,%20R-hadron,%20Expected">Mass Limit vs. Lifetime, R-hadron, Expected</a></li> <li><a href="?table=Mass%20Limit%20vs.%20Lifetime,%20R-hadron,%20Observed">Mass Limit vs. Lifetime, R-hadron, Observed</a></li> <li><a href="?table=Mass%20Limit%20vs.%20Lifetime,%20R-hadron,%20compressed,%20Expected">Mass Limit vs. Lifetime, R-hadron, compressed, Expected</a></li> <li><a href="?table=Mass%20Limit%20vs.%20Lifetime,%20R-hadron,%20compressed,%20Observed">Mass Limit vs. Lifetime, R-hadron, compressed, Observed</a></li> <li><a href="?table=Mass%20Limit%20vs.%20Lifetime,%20Chargino,%20Expected">Mass Limit vs. Lifetime, Chargino, Expected</a></li> <li><a href="?table=Mass%20Limit%20vs.%20Lifetime,%20Chargino,%20Observed">Mass Limit vs. Lifetime, Chargino, Observed</a></li> <li><a href="?table=Mass%20Limit%20vs.%20Lifetime,%20Stau,%20Expected">Mass Limit vs. Lifetime, Stau, Expected</a></li> <li><a href="?table=Mass%20Limit%20vs.%20Lifetime,%20Stau,%20Observed">Mass Limit vs. Lifetime, Stau, Observed</a></li> </ul> <b>Cross-section limit plots</b> <ul> <li><a href="?table=Cross%20Section%20Limit,%20R-hadron%201ns">Cross Section Limit, R-hadron 1ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20R-hadron%203ns">Cross Section Limit, R-hadron 3ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20R-hadron%2010ns">Cross Section Limit, R-hadron 10ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20R-hadron%2030ns">Cross Section Limit, R-hadron 30ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20R-hadron%20Stable">Cross Section Limit, R-hadron Stable</a></li> <li><a href="?table=Cross%20Section%20Limit,%20R-hadron%20Compressed%201ns">Cross Section Limit, R-hadron Compressed 1ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20R-hadron%20Compressed%203ns">Cross Section Limit, R-hadron Compressed 3ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20R-hadron%20Compressed%2010ns">Cross Section Limit, R-hadron Compressed 10ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20R-hadron%20Compressed%2030ns">Cross Section Limit, R-hadron Compressed 30ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20Chargino%201ns">Cross Section Limit, Chargino 1ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20Chargino%204ns">Cross Section Limit, Chargino 4ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20Chargino%2010ns">Cross Section Limit, Chargino 10ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20Chargino%2030ns">Cross Section Limit, Chargino 30ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20Chargino%20Stable">Cross Section Limit, Chargino Stable</a></li> <li><a href="?table=Cross%20Section%20Limit,%20Stau%201ns">Cross Section Limit, Stau 1ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20Stau%203ns">Cross Section Limit, Stau 3ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20Stau%2010ns">Cross Section Limit, Stau 10ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20Stau%2030ns">Cross Section Limit, Stau 30ns</a></li> <li><a href="?table=Cross%20Section%20Limit,%20Stau%20Stable">Cross Section Limit, Stau Stable</a></li> </ul> <b>Signal Region events projected to other kinematic variables</b> <ul> <li><a href="?table=SR-Inclusive_Low%20MET">SR-Inclusive_Low MET</a></li> <li><a href="?table=SR-Inclusive_High%20MET">SR-Inclusive_High MET</a></li> <li><a href="?table=SR-Inclusive_Low%20deltaPhi(MET,%20Track)">SR-Inclusive_Low deltaPhi(MET, Track)</a></li> <li><a href="?table=SR-Inclusive_High%20deltaPhi(MET,%20Track)">SR-Inclusive_High deltaPhi(MET, Track)</a></li> <li><a href="?table=SR-Inclusive_Low%20mT(MET,%20Track)">SR-Inclusive_Low mT(MET, Track)</a></li> <li><a href="?table=SR-Inclusive_High%20mT(MET,%20Track)">SR-Inclusive_High mT(MET, Track)</a></li> <li><a href="?table=SR-Inclusive_Low%20Leading%20jet%20pT">SR-Inclusive_Low Leading jet pT</a></li> <li><a href="?table=SR-Inclusive_High%20Leading%20jet%20pT">SR-Inclusive_High Leading jet pT</a></li> <li><a href="?table=SR-Inclusive_Low%20deltaPhi(Leading%20jet,%20Track)">SR-Inclusive_Low deltaPhi(Leading jet, Track)</a></li> <li><a href="?table=SR-Inclusive_High%20deltaPhi(Leading%20jet,%20Track)">SR-Inclusive_High deltaPhi(Leading jet, Track)</a></li> <li><a href="?table=SR-Inclusive_Low%20deltaPhi(MET,%20Leading%20jet)">SR-Inclusive_Low deltaPhi(MET, Leading jet)</a></li> <li><a href="?table=SR-Inclusive_High%20deltaPhi(MET,%20Leading%20jet)">SR-Inclusive_High deltaPhi(MET, Leading jet)</a></li> <li><a href="?table=SR-Inclusive_Low%20mT(MET,%20Leading%20jet)">SR-Inclusive_Low mT(MET, Leading jet)</a></li> <li><a href="?table=SR-Inclusive_High%20mT(MET,%20Leading%20jet)">SR-Inclusive_High mT(MET, Leading jet)</a></li> <li><a href="?table=SR-Inclusive_Low%20Effective%20mass">SR-Inclusive_Low Effective mass</a></li> <li><a href="?table=SR-Inclusive_High%20Effective%20mass">SR-Inclusive_High Effective mass</a></li> </ul> <b>Acceptance and efficiency values for reinterpretation</b> <ul> <li><a href="?table=Muon%20Reconstruction%20Efficiency%20distribution">Muon Reconstruction Efficiency distribution</a></li> <li><a href="?table=Muon%20Reconstruction%20Efficiency,%20R-hadron%20distribution">Muon Reconstruction Efficiency, R-hadron distribution</a></li> <li><a href="?table=Trigger%20Efficiency%20distribution">Trigger Efficiency distribution</a></li> <li><a href="?table=Event%20Selection%20Efficiency%20distribution">Event Selection Efficiency distribution</a></li> <li><a href="?table=Track%20Selection%20Efficiency%20distribution">Track Selection Efficiency distribution</a></li> <li><a href="?table=Mass%20Window%20Efficiency">Mass Window Efficiency</a></li> </ul> <b>Acceptance and efficiency tables for signal samples</b> <ul> <li><a href="?table=Acceptance,%20R-hadron">Acceptance, R-hadron</a></li> <li><a href="?table=Acceptance,%20R-hadron,%20compressed">Acceptance, R-hadron, compressed</a></li> <li><a href="?table=Acceptance,%20Chargino">Acceptance, Chargino</a></li> <li><a href="?table=Acceptance,%20Stau">Acceptance, Stau</a></li> </ul> <ul> <li><a href="?table=Event-level%20efficiency,%20R-hadron">Event-level efficiency, R-hadron</a></li> <li><a href="?table=Event-level%20efficiency,%20R-hadron,%20compressed">Event-level efficiency, R-hadron, compressed</a></li> <li><a href="?table=Event-level%20efficiency,%20Chargino">Event-level efficiency, Chargino</a></li> <li><a href="?table=Event-level%20efficiency,%20Stau">Event-level efficiency, Stau</a></li> </ul> <ul> <li><a href="?table=Efficiency,%20SR-Inclusve_High,%20R-hadron">Efficiency, SR-Inclusve_High, R-hadron</a></li> <li><a href="?table=Efficiency,%20SR-Inclusve_High,%20R-hadron,%20compressed">Efficiency, SR-Inclusve_High, R-hadron, compressed</a></li> <li><a href="?table=Efficiency,%20SR-Inclusve_High,%20Chargino">Efficiency, SR-Inclusve_High, Chargino</a></li> <li><a href="?table=Efficiency,%20SR-Inclusve_High,%20Stau">Efficiency, SR-Inclusve_High, Stau</a></li> </ul> <ul> <li><a href="?table=Efficiency,%20SR-Inclusive_Low,%20R-hadron">Efficiency, SR-Inclusive_Low, R-hadron</a></li> <li><a href="?table=Efficiency,%20SR-Inclusive_Low,%20R-hadron,%20compressed">Efficiency, SR-Inclusive_Low, R-hadron, compressed</a></li> <li><a href="?table=Efficiency,%20SR-Inclusive_Low,%20Chargino">Efficiency, SR-Inclusive_Low, Chargino</a></li> <li><a href="?table=Efficiency,%20SR-Inclusive_Low,%20Stau">Efficiency, SR-Inclusive_Low, Stau</a></li> </ul> <b>Cut flow for signal samples</b> <ul> <li><a href="?table=Cut%20Flow,%20R-hadron">Cut Flow, R-hadron</a></li> <li><a href="?table=Cut%20Flow,%20R-hadron,%20compressed">Cut Flow, R-hadron, compressed</a></li> <li><a href="?table=Cut%20Flow,%20Chargino">Cut Flow, Chargino</a></li> <li><a href="?table=Cut%20Flow,%20Stau">Cut Flow, Stau</a></li> </ul>
Comparison of the observed and expected VAR distributionsin VR-LowPt-Inclusive_High. The band on the expected background estimation indicates the total uncertainty of the estimation. Downward triangle markers at the bottom of the panels indicate there is no events observed in the corresponding bin, while upward triangle markers at the bottom panel indicate the observed data is beyond the range.
Comparison of the observed and expected VAR distributionsin VR-HiEta-Inclusive. The band on the expected background estimation indicates the total uncertainty of the estimation. Downward triangle markers at the bottom of the panels indicate there is no events observed in the corresponding bin, while upward triangle markers at the bottom panel indicate the observed data is beyond the range.
A search for a new heavy scalar or pseudo-scalar Higgs boson ($H/A$) produced in association with a pair of top quarks, with the Higgs boson decaying into a pair of top quarks ($H/A\rightarrow t\bar{t}$) is reported. The search targets a final state with exactly two leptons with same-sign electric charges or at least three leptons. The analysed dataset corresponds to an integrated luminosity of 139 fb$^{-1}$ of proton-proton collisions collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Two multivariate classifiers are used to separate the signal from the background. No significant excess of events over the Standard Model expectation is observed. The results are interpreted in the context of a type-II two-Higgs-doublet model. The observed (expected) upper limits at 95% confidence level on the $t\bar{t}H/A$ production cross-section times the branching ratio of $H/A\rightarrow t\bar{t}$ range between 14 (10) fb and 6 (5) fb for a heavy Higgs boson with mass between 400 GeV and 1000 GeV, respectively. Assuming that only one particle, either the scalar $H$ or the pseudo-scalar $A$, contributes to the $t\bar{t}t\bar{t}$ final state, values of $\tan\beta$ below 1.2 or 0.5 are excluded for a mass of 400 GeV or 1000 GeV, respectively. These exclusion ranges increase to $\tan\beta$ below 1.6 or 0.6 when both particles are considered.
Pre-fit comparison between data and background in the baseline SR for two of the variables used as input for the SM BDT: the sum of the leading four jets b-tagging scores.
Pre-fit comparison between data and background in the baseline SR for two of the variables used as input for the SM BDT: the number of jets.
Pre-fit comparison between data and background in the baseline SR for two of the variables used as input for the BSM pBDT: SM BDT.
The correlations between flow harmonics $v_n$ for $n=2$, 3 and 4 and mean transverse momentum $[p_\mathrm{T}]$ in $^{129}$Xe+$^{129}$Xe and $^{208}$Pb+$^{208}$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.44$ TeV and 5.02 TeV, respectively, are measured using charged particles with the ATLAS detector. The correlations are sensitive to the shape and size of the initial geometry, nuclear deformation, and initial momentum anisotropy. The effects from non-flow and centrality fluctuations are minimized, respectively, via a subevent cumulant method and event activity selection based on particle production in the very forward rapidity. The results show strong dependences on centrality, harmonic number $n$, $p_{\mathrm{T}}$ and pseudorapidity range. Current models describe qualitatively the overall centrality- and system-dependent trends but fail to quantitatively reproduce all the data. In the central collisions, where models generally show good agreement, the $v_2$-$[p_\mathrm{T}]$ correlations are sensitive to the triaxiality of the quadruple deformation. The comparison of model to the Pb+Pb and Xe+Xe data suggests that the $^{129}$Xe nucleus is a highly deformed triaxial ellipsoid that is neither a prolate nor an oblate shape. This provides strong evidence for a triaxial deformation of $^{129}$Xe nucleus using high-energy heavy-ion collision.
$\rho_{2}$ Standard method, for Pb+Pb 5.02 TeV, $|\eta|$<2.5, 0.5< $p_{T}$ <5.0 GeV vs $\Sigma E_{T}$ based Centrality
$\rho_{2}$ Two_subevent method, for Pb+Pb 5.02 TeV, $|\eta|$<2.5, 0.5< $p_{T}$ <5.0 GeV vs $\Sigma E_{T}$ based Centrality
$\rho_{2}$ Three_subevent method, for Pb+Pb 5.02 TeV, $|\eta|$<2.5, 0.5< $p_{T}$ <5.0 GeV vs $\Sigma E_{T}$ based Centrality
This paper presents direct searches for lepton flavour violation in Higgs boson decays, $H\rightarrow e\tau$ and $H\rightarrow\mu\tau$, performed using data collected with the ATLAS detector at the LHC. The searches are based on a data sample of proton-proton collisions at a centre-of-mass energy $\sqrt{s} = 13$ TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. Leptonic ($\tau \rightarrow \ell \nu_\ell \nu_\tau$) and hadronic ($\tau \rightarrow $ hadrons $ \nu_\tau$) decays of the $\tau$-lepton are considered. Two background estimation techniques are employed: the MC-template method, based on data-corrected simulation samples, and the Symmetry method, based on exploiting the symmetry between electrons and muons in the Standard Model backgrounds. No significant excess of events is observed and the results are interpreted as upper limits on lepton-flavour-violating branching ratios of the Higgs boson. The observed (expected) upper limits set on the branching ratios at 95% confidence level, $\mathcal{B}(H\rightarrow e\tau)<0.20\%$ (0.12%) and $\mathcal{B}(H\rightarrow \mu\tau)<0.18\%$ (0.09%), are obtained with the MC-template method from a simultaneous measurement of potential $H \rightarrow e\tau$ and $H \rightarrow\mu\tau$ signals. The best-fit branching ratio difference, $\mathcal{B}(H\rightarrow \mu\tau)- \mathcal{B}(H\rightarrow e\tau)$, measured with the Symmetry method in the channel where the $\tau$-lepton decays to leptons, is (0.25 $\pm$ 0.10)%, compatible with a value of zero within 2.5$\sigma$.
Fit results of the simultaneous measurements of the $H\to e\tau$ and $H\to \mu\tau$ signals (2POI) showing upper limits at 95% C.L. on the LFV branching ratios of the Higgs boson $H\to e\tau$. The results from standalone channel/categories fits are compared with the results of the combined fit.
Fit results of the simultaneous measurements of the $H\to e\tau$ and $H\to \mu\tau$ signals (2POI) showing best-fit values of the LFV branching ratios of the Higgs boson $\hat{B}$($H\to e\tau$). The results from standalone channel/categories fits are compared with the results of the combined fit.
Fit results of the simultaneous measurements of the $H\to e\tau$ and $H\to \mu\tau$ signals (2POI) showing upper limits at 95% C.L. on the LFV branching ratios of the Higgs boson $H\to \mu\tau$. The results from standalone channel/categories fits are compared with the results of the combined fit.
A search for the leptonic charge asymmetry ($A_\text{c}^{\ell}$) of top-quark$-$antiquark pair production in association with a $W$ boson ($t\bar{t}W$) is presented. The search is performed using final states with exactly three charged light leptons (electrons or muons) and is based on $\sqrt{s} = 13$ TeV proton$-$proton collision data collected with the ATLAS detector at the Large Hadron Collider at CERN during the years 2015$-$2018, corresponding to an integrated luminosity of 139 fb$^{-1}$. A profile-likelihood fit to the event yields in multiple regions corresponding to positive and negative differences between the pseudorapidities of the charged leptons from top-quark and top-antiquark decays is used to extract the charge asymmetry. At reconstruction level, the asymmetry is found to be $-0.123 \pm 0.136$ (stat.) $\pm \, 0.051$ (syst.). An unfolding procedure is applied to convert the result at reconstruction level into a charge-asymmetry value in a fiducial volume at particle level with the result of $-0.112 \pm 0.170$ (stat.) $\pm \, 0.054$ (syst.). The Standard Model expectations for these two observables are calculated using Monte Carlo simulations with next-to-leading-order plus parton shower precision in quantum chromodynamics and including next-to-leading-order electroweak corrections. They are $-0.084 \, ^{+0.005}_{-0.003}$ (scale) $\pm\, 0.006$ (MC stat.) and $-0.063 \, ^{+0.007}_{-0.004}$ (scale) $\pm\, 0.004$ (MC stat.) respectively, and in agreement with the measurements.
Measured values of the leptonic charge asymmetry ($A_c^{\ell}$) in ttW production in the three lepton channel. Results are given at reconstruction level and at particle level. Expected values are obtained using the Sherpa MC generator.
Definition of the fiducial phase space at particle level with the light lepton candidates $(\ell=e,\mu)$, jets ($j$) and invariant mass of the opposite sign same flavour lepton pair ($m_{OSSF}^{ll}$).
Correlation matrix between the Normalisation Factors and the Nuisance Parameters (NP) in the fit using using both statistical and systematic uncertainties to data in all analysis regions.