A search for Higgs boson pair production via vector-boson fusion (VBF) in the $b\bar{b}b\bar{b}$ final state is carried out with the ATLAS experiment, using 126 fb$^{-1}$ of proton-proton collision data delivered at $\sqrt{s} = 13$ TeV by the Large Hadron Collider. This search is sensitive to VBF production of additional heavy bosons that may decay into Higgs boson pairs, and in a non-resonant topology it can constrain the quartic coupling between the Higgs bosons and vector bosons. No significant excess, relative to the background-only Standard Model expectation, is observed, and limits on the production cross-section are set at the 95% confidence level for a heavy scalar resonance in the context of an extended Higgs sector, and for non-resonant Higgs boson pair production. Interpretation in terms of the coupling between a Higgs boson pair and two vector bosons is also provided: coupling values normalised to the Standard Model expectation of $\kappa_{2V} < -0.56$ and $\kappa_{2V} > 2.89$ are excluded at the 95% confidence level in data.
Acceptance x efficiency versus $\kappa_{2V}$ for non-resonant signal of $HH$.
Acceptance x efficiency versus resonance mass for both narrow and broad resonance $X$ to $HH$.
Post-fit mass distribution of the $HH$ candidates in the signal region. The expected background is shown after the profile-likelihood fit to data with the background-only hypothesis; the narrow-width resonant signal at 800 GeV and the non-resonant signal at $\kappa_{2V}$ = 3 are overlaid, both normalised to the corresponding observed upper limits on the cross-section.
This paper presents results of searches for electroweak production of supersymmetric particles in models with compressed mass spectra. The searches use 139 fb$^{-1}$ of $\sqrt{s}=13$ TeV proton-proton collision data collected by the ATLAS experiment at the Large Hadron Collider. Events with missing transverse momentum and two same-flavor, oppositely charged, low transverse momentum leptons are selected, and are further categorized by the presence of hadronic activity from initial-state radiation or a topology compatible with vector-boson fusion processes. The data are found to be consistent with predictions from the Standard Model. The results are interpreted using simplified models of $R$-parity-conserving supersymmetry in which the lightest supersymmetric partner is a neutralino with a mass similar to the lightest chargino, the second-to-lightest neutralino or the slepton. Lower limits on the masses of charginos in different simplified models range from 193 GeV to 240 GeV for moderate mass splittings, and extend down to mass splittings of 1.5 GeV to 2.4 GeV at the LEP chargino bounds (92.4 GeV). Similar lower limits on degenerate light-flavor sleptons extend up to masses of 251 GeV and down to mass splittings of 550 MeV. Constraints on vector-boson fusion production of electroweak SUSY states are also presented.
Number of signal events in SR-E-1L1T for the (m($\tilde{\chi}_{2}^{0}$),m($\tilde{\chi}_{1}^{0}$)) = (155 GeV, 150 GeV) Higgsino signal model at different stages of selection before and after weighting events to correspond to 140/fb.
Number of signal events in SR-E-high for the (m($\tilde{\chi}_{2}^{0}$),m($\tilde{\chi}_{1}^{0}$)) = (155 GeV, 150 GeV) Higgsino signal model at different stages of selection before and after weighting events to correspond to 140/fb.
Number of signal events in SR-E-low for the (m($\tilde{\chi}_{2}^{0}$),m($\tilde{\chi}_{1}^{0}$)) = (155 GeV, 150 GeV) Higgsino signal model at different stages of selection before and after weighting events to correspond to 140/fb.
A search for the direct production of the supersymmetric partners of $\tau$-leptons (staus) in final states with two hadronically decaying $\tau$-leptons is presented. The analysis uses a dataset of $pp$ collisions corresponding to an integrated luminosity of $139$ fb$^{-1}$, recorded with the ATLAS detector at the Large Hadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected Standard Model background is observed. Limits are derived in scenarios of direct production of stau pairs with each stau decaying into the stable lightest neutralino and one $\tau$-lepton in simplified models where the two stau mass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidence level for a massless lightest neutralino.
The observed upper limits on the model cross-section in units of pb for simplified models with combined ${\tilde{\tau}}^{+}_{R,L} {\tilde{\tau}}^{-}_{R,L}$ production. Three points at ${M({\tilde{\chi}}^{0}_{1})}=200GeV$ were removed from the plot but kept in the table because they overlapped with the plot's legend and are far from the exclusion contour.
The expected 95% CL exclusion contours for the combined fit of SR-lowMass and SR-highMass for simplified models with combined ${\tilde{\tau}}^{+}_{R,L} {\tilde{\tau}}^{-}_{R,L}$ production.
The observed 95\% CL exclusion contours for the combined fit of SR-lowMass and SR-highMass for simplified models with combined ${\tilde{\tau}}^{+}_{R,L} {\tilde{\tau}}^{-}_{R,L}$ production.
The production of a prompt photon in association with a $Z$ boson is studied in proton-proton collisions at a centre-of-mass energy $\sqrt{s} =$ 13 TeV. The analysis uses a data sample with an integrated luminosity of 139 fb$^{-1}$ collected by the ATLAS detector at the LHC from 2015 to 2018. The production cross-section for the process $pp \rightarrow \ell^+\ell^-\gamma+X$ ($\ell = e, \mu$) is measured within a fiducial phase-space region defined by kinematic requirements on the photon and the leptons, and by isolation requirements on the photon. An experimental precision of 2.9% is achieved for the fiducial cross-section. Differential cross-sections are measured as a function of each of six kinematic variables characterising the $\ell^+\ell^-\gamma$ system. The data are compared with theoretical predictions based on next-to-leading-order and next-to-next-to-leading-order perturbative QCD calculations. The impact of next-to-leading-order electroweak corrections is also considered.
The measured fiducial cross section. "Uncor" uncertainty includes all systematic uncertainties that are uncorrelated between electron and muon channels such as the uncertainty on the electron identification efficiency and the uncorrelated component of the background uncertainties. The parton-to-particle correction factor $C_{theory}$ is the ratio of the cross-section predicted by Sherpa LO samples at particle level within the fiducial phase-space region defined in Table 4 to the predicted cross-section at parton level within the same fiducial region but with the smooth-cone isolation prescription defined above replacing the particle-level photon isolation criterion, and with Born-level leptons in place of dressed leptons. This correction should be applied on fixed order parton-level calculations. The systematic uncertainty is evaluated from a comparison with the correction factor obtained using events generated with SHERPA 2.2.2 at NLO. In the case that the calculations are valid for dressed leptons, a modified correction factor excluding the Born-to-dressed lepton correction should be applied instead. This correction only takes into account the particle-level isolation criteria, and is provided separately here. The Sherpa 2.2.8 NLO cross-sections given below include a small contribution from EW $Z\gamma jj$ production of 4.57 fb.
The measured fiducial cross section vs $E_{\mathrm{T}}^\gamma$. The central values are provided along with the statistical and systematic uncertainties together with the sign information. The statistical and "Uncor" uncertainty should be treated as uncorrelated bin-to-bin, while the rest are correlated between bins, and they are written as signed NP variations. The parton-to-particle correction factor $C_{theory}$ is the ratio of the cross-section predicted by Sherpa LO samples at particle level within the fiducial phase-space region defined in Table 4 to the predicted cross-section at parton level within the same fiducial region but with the smooth-cone isolation prescription defined above replacing the particle-level photon isolation criterion, and with Born-level leptons in place of dressed leptons. This correction should be applied on fixed order parton-level calculations. The systematic uncertainty is evaluated from a comparison with the correction factor obtained using events generated with SHERPA 2.2.2 at NLO. In the case that the calculations are valid for dressed leptons, a modified correction factor excluding the Born-to-dressed lepton correction should be applied instead. This correction only takes into account the particle-level isolation criteria, and is provided separately here. The Sherpa 2.2.8 NLO cross-sections given below include a small contribution from EW $Z\gamma jj$ production.
The measured fiducial cross section vs $|\eta^\gamma|$. The central values are provided along with the statistical and systematic uncertainties together with the sign information. The statistical and "Uncor" uncertainty should be treated as uncorrelated bin-to-bin, while the rest are correlated between bins, and they are written as signed NP variations. The parton-to-particle correction factor $C_{theory}$ is the ratio of the cross-section predicted by Sherpa LO samples at particle level within the fiducial phase-space region defined in Table 4 to the predicted cross-section at parton level within the same fiducial region but with the smooth-cone isolation prescription defined above replacing the particle-level photon isolation criterion, and with Born-level leptons in place of dressed leptons. This correction should be applied on fixed order parton-level calculations. The systematic uncertainty is evaluated from a comparison with the correction factor obtained using events generated with SHERPA 2.2.2 at NLO. In the case that the calculations are valid for dressed leptons, a modified correction factor excluding the Born-to-dressed lepton correction should be applied instead. This correction only takes into account the particle-level isolation criteria, and is provided separately here. The Sherpa 2.2.8 NLO cross-sections given below include a small contribution from EW $Z\gamma jj$ production.
The results of a search for electroweakino pair production $pp \rightarrow \tilde\chi^\pm_1 \tilde\chi^0_2$ in which the chargino ($\tilde\chi^\pm_1$) decays into a $W$ boson and the lightest neutralino ($\tilde\chi^0_1$), while the heavier neutralino ($\tilde\chi^0_2$) decays into the Standard Model 125 GeV Higgs boson and a second $\tilde\chi^0_1$ are presented. The signal selection requires a pair of $b$-tagged jets consistent with those from a Higgs boson decay, and either an electron or a muon from the $W$ boson decay, together with missing transverse momentum from the corresponding neutrino and the stable neutralinos. The analysis is based on data corresponding to 139 $\mathrm{fb}^{-1}$ of $\sqrt{s}=13$ TeV $pp$ collisions provided by the Large Hadron Collider and recorded by the ATLAS detector. No statistically significant evidence of an excess of events above the Standard Model expectation is found. Limits are set on the direct production of the electroweakinos in simplified models, assuming pure wino cross-sections. Masses of $\tilde{\chi}^{\pm}_{1}/\tilde{\chi}^{0}_{2}$ up to 740 GeV are excluded at 95% confidence level for a massless $\tilde{\chi}^{0}_{1}$.
Signal acceptance in SR-HM for simplified models with $\tilde\chi^\pm_1 \tilde\chi^0_2 \rightarrow Wh\tilde\chi^0_1\tilde\chi^0_1, W \rightarrow l\nu, h \rightarrow b\bar{b}$ production. 1lb\bar{b}$ production
Signal acceptance in SR-HM high $m_{CT}$ for simplified models with $\tilde\chi^\pm_1 \tilde\chi^0_2 \rightarrow Wh\tilde\chi^0_1\tilde\chi^0_1, W \rightarrow l\nu, h \rightarrow b\bar{b}$ production.
Signal acceptance in SR-HM low $m_{CT}$ for simplified models with $\tilde\chi^\pm_1 \tilde\chi^0_2 \rightarrow Wh\tilde\chi^0_1\tilde\chi^0_1, W \rightarrow l\nu, h \rightarrow b\bar{b}$ production.
A search for supersymmetric partners of gluons and quarks is presented, involving signatures with jets and either two isolated leptons (electrons or muons) with the same electric charge, or at least three isolated leptons. A data sample of proton-proton collisions at $\sqrt{s}$ = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider between 2015 and 2018, corresponding to a total integrated luminosity of 139 fb$^{-1}$, is used for the search. No significant excess over the Standard Model expectation is observed. The results are interpreted in simplified supersymmetric models featuring both R-parity conservation and R-parity violation, raising the exclusion limits beyond those of previous ATLAS searches to 1600 GeV for gluino masses and 750 GeV for bottom and top squark masses in these scenarios.
Best observed 95% CL exclusion contours selected from Rpc2L1b and Rpc2L2b on the lightest bottom squark and lightest neutralino masses in a SUSY scenario where pairs of bottom-antibottom squarks are produced and decay into the lightest neutralino via a chargino, $\tilde b^{}_{1}\to t\tilde{\chi}_1^-$ followed by $\tilde{\chi}_1^\pm\to W^\pm\tilde{\chi}_1^0$.
Number of signal events expected for 139 fb$^{-1}$ at different stages of the event selection for the signal region Rpc2L0b, in a SUSY scenario where gluinos are produced in pairs and decay into the lightest neutralino via a two-steps cascade, $\tilde g\to q\bar{q}^{'}\tilde{\chi}_1^\pm$ followed by $\tilde{\chi}_1^\pm\to W^\pm\tilde{\chi}_2^0$ and $\tilde{\chi}_2^0\to Z\tilde{\chi}_1^0$. The masses of the superpartners involved in the process are set to $m(\tilde g)$ = 1600 GeV, $m(\tilde \chi_1^\pm)$ = 1200 GeV, $m(\tilde \chi_2^0)$ = 1000 GeV and $m(\tilde \chi_1^0)$ = 800 GeV. Only statistical uncertainties are shown.
Number of signal events expected for 139 fb$^{-1}$ at different stages of the event selection for the signal region Rpc2L1b, in a SUSY scenario where pairs of bottom-antibottom squarks are produced and decay into the lightest neutralino via a chargino, $\tilde b^{}_{1}\to t\tilde{\chi}_1^-$ followed by $\tilde{\chi}_1^\pm\to W^\pm\tilde{\chi}_1^0$. The masses of the superpartners involved in the process are set to $m(\tilde{b}^{}_1)$ = 850 GeV, $m(\tilde \chi_1^\pm)$ = 500 GeV and $m(\tilde \chi_1^0)$ = 400 GeV. Only statistical uncertainties are shown.
Several models of physics beyond the Standard Model predict the existence of dark photons, light neutral particles decaying into collimated leptons or light hadrons. This paper presents a search for long-lived dark photons produced from the decay of a Higgs boson or a heavy scalar boson and decaying into displaced collimated Standard Model fermions. The search uses data corresponding to an integrated luminosity of 36.1 fb$^{-1}$ collected in proton-proton collisions at $\sqrt{s} =$ 13 TeV recorded in 2015-2016 with the ATLAS detector at the Large Hadron Collider. The observed number of events is consistent with the expected background, and limits on the production cross section times branching fraction as a function of the proper decay length of the dark photon are reported. A cross section times branching fraction above 4 pb is excluded for a Higgs boson decaying into two dark photons for dark-photon decay lengths between 1.5 mm and 307 mm.
Upper limits at 95% CL on the cross section times branching fraction for the process $H \to 2\gamma_d + X$ with $m_H$ = 125 GeV in the muon-muon final state.
Upper limits at 95% CL on the cross section times branching fraction for the process $H \to 4\gamma_d + X$ with $m_H$ = 125 GeV in the muon-muon final state.
Upper limits at 95% CL on the cross section times branching fraction for the process $H \to 2\gamma_d + X$ with $m_H$ = 800 GeV in the muon-muon final state.
A search for flavour-changing neutral current (FCNC) events via the coupling of a top quark, a photon, and an up or charm quark is presented using 81 fb −1 of proton–proton collision data taken at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Events with a photon, an electron or muon, a b -tagged jet, and missing transverse momentum are selected. A neural network based on kinematic variables differentiates between events from signal and background processes. The data are consistent with the background-only hypothesis, and limits are set on the strength of the tqγ coupling in an effective field theory. These are also interpreted as 95% CL upper limits on the cross section for FCNC tγ production via a left-handed (right-handed) tuγ coupling of 36 fb (78 fb) and on the branching ratio for t→γu of 2.8×10−5 ( 6.1×10−5 ). In addition, they are interpreted as 95% CL upper limits on the cross section for FCNC tγ production via a left-handed (right-handed) tcγ coupling of 40 fb (33 fb) and on the branching ratio for t→γc of 22×10−5 ( 18×10−5 ).
Observed (expected) 95 % CL limits on the effective coupling strengths for different vertices and couplings, the production cross section, and the branching ratio. For the former, the energy scale is assumed to be $\Lambda$ = 1 TeV.
Post-fit distributions of a background-only fit to the SR and the CRs of the NN output in the SR for the $tu\gamma$ right-handed coupling. In addition, the expected signal is overlaid for an effective coupling strength corresponding to the observed limit multiplied by a factor of ten.
Post-fit distributions of a background-only fit to the SR and the CRs of the NN output in the SR for the $tc\gamma$ left-handed coupling. In addition, the expected signal is overlaid for an effective coupling strength corresponding to the observed limit multiplied by a factor of ten.
A search for the electroweak production of charginos and sleptons decaying into final states with two electrons or muons is presented. The analysis is based on 139 fb$^{-1}$ of proton-proton collisions recorded by the ATLAS detector at the Large Hadron Collider at $\sqrt{s}=13$ TeV. Three $R$-parity-conserving scenarios where the lightest neutralino is the lightest supersymmetric particle are considered: the production of chargino pairs with decays via either $W$ bosons or sleptons, and the direct production of slepton pairs. The analysis is optimised for the first of these scenarios, but the results are also interpreted in the others. No significant deviations from the Standard Model expectations are observed and limits at 95 % confidence level are set on the masses of relevant supersymmetric particles in each of the scenarios. For a massless lightest neutralino, masses up to 420 GeV are excluded for the production of the lightest-chargino pairs assuming $W$-boson-mediated decays and up to 1 TeV for slepton-mediated decays, whereas for slepton-pair production, masses up to 700 GeV are excluded assuming three generations of mass-degenerate sleptons.
- - - - - - - - Overview of HEPData Record - - - - - - - - <br/><br/> <b>Background Fit results:</b> <ul> <li><a href="89413?version=1&table=Backgroundfit1">CRs</a> <li><a href="89413?version=1&table=Backgroundfit2">VRs</a> <li><a href="89413?version=1&table=Backgroundfit5">inclusive DF-0J SRs</a> <li><a href="89413?version=1&table=Backgroundfit6">inclusive DF-1J SRs</a> <li><a href="89413?version=1&table=Backgroundfit3">inclusive SF-0J SRs</a> <li><a href="89413?version=1&table=Backgroundfit4">inclusive SF-1J SRs</a> </ul> <b>Kinematic distributions in VRs:</b> <ul> <li><a href="89413?version=1&table=VRkinematics1">$m_{T2}$ in VR-top-low</a> <li><a href="89413?version=1&table=VRkinematics2">$m_{T2}$ in VR-top-high</a> <li><a href="89413?version=1&table=VRkinematics3">$E_T^{miss}$ in VR-WW-0J</a> <li><a href="89413?version=1&table=VRkinematics4">$E_T^{miss}$ in VR-WW-1J</a> <li><a href="89413?version=1&table=VRkinematics5">$E_T^{miss}$ sig in VR-VZ</a> <li><a href="89413?version=1&table=VRkinematics6">$E_T^{miss}$ sig in VR-top-WW</a> </ul> <b>Kinematic distributions in SRs:</b> <ul> <li><a href="89413?version=1&table=SRkinematics1">$m_{T2}$ in SR-SF-0J</a> <li><a href="89413?version=1&table=SRkinematics2">$m_{T2}$ in SR-SF-1J</a> <li><a href="89413?version=1&table=SRkinematics3">$m_{T2}$ in SR-DF-0J</a> <li><a href="89413?version=1&table=SRkinematics4">$m_{T2}$ in SR-DF-1J</a> </ul> <b>Systematic uncertaities:</b> <ul> <li><a href="89413?version=1&table=Systematic uncertainties">dominant systematic uncertainties in the inclusive SRs</a> </ul> <b>Exclusion contours:</b> <ul> <li><a href="89413?version=1&table=Exclusioncontour(obs)1">expected exclusion contour direct chargino-pair production via W decay grid</a> <li><a href="89413?version=1&table=Exclusioncontour(exp)1">observed exclusion contour direct chargino-pair production via W decay grid</a> <li><a href="89413?version=1&table=Exclusioncontour(obs)2">expected exclusion contour direct chargino-pair production via slepton decay grid</a> <li><a href="89413?version=1&table=Exclusioncontour(exp)2">observed exclusion contour direct chargino-pair production via slepton decay grid</a> <li><a href="89413?version=1&table=Exclusioncontour(obs)3">expected exclusion contour direct slepton-pair production grid</a> <li><a href="89413?version=1&table=Exclusioncontour(exp)3">observed exclusion contour direct slepton-pair production grid</a> </ul> <br/><br/><b>AUXILIARY MATERIAL</b><br/> <b>Background Fit in binned SRs:</b> <ul> <li><a href="89413?version=1&table=Backgroundfit7">binned DF-0J SRs</a> <li><a href="89413?version=1&table=Backgroundfit8">binned DF-1J SRs</a> <li><a href="89413?version=1&table=Backgroundfit9">binned SF-0J SRs</a> <li><a href="89413?version=1&table=Backgroundfit10">binned SF-1J SRs</a> </ul> <b>Exclusion contours:</b> <ul> <li><a href="89413?version=1&table=Exclusioncontour(obs)4">expected exclusion contour left-handed slepton-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(exp)4">observed exclusion contour left-handed slepton-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(obs)5">expected exclusion contour right-handed slepton-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(exp)5">observed exclusion contour right-handed slepton-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(obs)6">expected exclusion contour selectron-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(exp)6">observed exclusion contour selectron-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(obs)7">expected exclusion contour left-handed selectron-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(exp)7">observed exclusion contour left-handed selectron-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(obs)8">expected exclusion contour right-handed selectron-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(exp)8">observed exclusion contour right-handed selectron-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(obs)9">expected exclusion contour smuon-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(exp)9">observed exclusion contour smuon-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(obs)10">expected exclusion contour left-handed smuon-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(exp)10">observed exclusion contour left-handed smuon-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(obs)11">expected exclusion contour right-handed smuon-pair production</a> <li><a href="89413?version=1&table=Exclusioncontour(exp)11">observed exclusion contour right-handed smuon-pair production</a> </ul> <b>Cross section upper limits:</b> <ul> <li><a href="89413?version=1&table=xsecupperlimits1">upper limits on signal cross section for direct chargino-pair production via W decay</a> <li><a href="89413?version=1&table=xsecupperlimits2">upper limits on signal cross section for direct chargino-pair production via slepton decay</a> <li><a href="89413?version=1&table=xsecupperlimits3">upper limits on signal cross section for direct slepton-pair production</a> </ul> <b>Acceptances and Efficiencies for direct chargino-pair production via W decay grid </b> <ul> <li> <b>Acceptance</b> <br/> <a href="89413?version=1&table=AcceptanceSR-DF-0J-[100,inf)forC1C1WWgrid">SR-DF-0J-[100,inf) </a> <a href="89413?version=1&table=AcceptanceSR-DF-0J-[160,inf)forC1C1WWgrid">SR-DF-0J-[160,inf) </a> <a href="89413?version=1&table=AcceptanceSR-DF-0J-[100,120)forC1C1WWgrid">SR-DF-0J-[100,120) </a> <a href="89413?version=1&table=AcceptanceSR-DF-0J-[120,160)forC1C1WWgrid">SR-DF-0J-[120,160) </a> <a href="89413?version=1&table=AcceptanceSR-DF-0J-[100,105)forC1C1WWgrid">SR-DF-0J-[100,105) </a> <a href="89413?version=1&table=AcceptanceSR-DF-0J-[105,110)forC1C1WWgrid">SR-DF-0J-[105,110) </a> <a href="89413?version=1&table=AcceptanceSR-DF-0J-[110,120)forC1C1WWgrid">SR-DF-0J-[110,120) </a> <a href="89413?version=1&table=AcceptanceSR-DF-0J-[120,140)forC1C1WWgrid">SR-DF-0J-[120,140) </a> <a href="89413?version=1&table=AcceptanceSR-DF-0J-[140,160)forC1C1WWgrid">SR-DF-0J-[140,160) </a> <a href="89413?version=1&table=AcceptanceSR-DF-0J-[160,180)forC1C1WWgrid">SR-DF-0J-[160,180) </a> <a href="89413?version=1&table=AcceptanceSR-DF-0J-[180,220)forC1C1WWgrid">SR-DF-0J-[180,220) </a> <a href="89413?version=1&table=AcceptanceSR-DF-0J-[220,260)forC1C1WWgrid">SR-DF-0J-[220,260) </a> <a href="89413?version=1&table=AcceptanceSR-DF-0J-[260,inf)forC1C1WWgrid">SR-DF-0J-[260,inf) </a><br/> <a href="89413?version=1&table=AcceptanceSR-DF-1J-[100,inf)forC1C1WWgrid">SR-DF-1J-[100,inf) </a> <a href="89413?version=1&table=AcceptanceSR-DF-1J-[160,inf)forC1C1WWgrid">SR-DF-1J-[160,inf) </a> <a href="89413?version=1&table=AcceptanceSR-DF-1J-[100,120)forC1C1WWgrid">SR-DF-1J-[100,120) </a> <a href="89413?version=1&table=AcceptanceSR-DF-1J-[120,160)forC1C1WWgrid">SR-DF-1J-[120,160) </a> <a href="89413?version=1&table=AcceptanceSR-DF-1J-[100,105)forC1C1WWgrid">SR-DF-1J-[100,105) </a> <a href="89413?version=1&table=AcceptanceSR-DF-1J-[105,110)forC1C1WWgrid">SR-DF-1J-[105,110) </a> <a href="89413?version=1&table=AcceptanceSR-DF-1J-[110,120)forC1C1WWgrid">SR-DF-1J-[110,120) </a> <a href="89413?version=1&table=AcceptanceSR-DF-1J-[120,140)forC1C1WWgrid">SR-DF-1J-[120,140) </a> <a href="89413?version=1&table=AcceptanceSR-DF-1J-[140,160)forC1C1WWgrid">SR-DF-1J-[140,160) </a> <a href="89413?version=1&table=AcceptanceSR-DF-1J-[160,180)forC1C1WWgrid">SR-DF-1J-[160,180) </a> <a href="89413?version=1&table=AcceptanceSR-DF-1J-[180,220)forC1C1WWgrid">SR-DF-1J-[180,220) </a> <a href="89413?version=1&table=AcceptanceSR-DF-1J-[220,260)forC1C1WWgrid">SR-DF-1J-[220,260) </a> <a href="89413?version=1&table=AcceptanceSR-DF-1J-[260,inf)forC1C1WWgrid">SR-DF-1J-[260,inf) </a><br/> <a href="89413?version=1&table=AcceptanceSR-SF-0J-[100,inf)forC1C1WWgrid">SR-SF-0J-[100,inf) </a> <a href="89413?version=1&table=AcceptanceSR-SF-0J-[160,inf)forC1C1WWgrid">SR-SF-0J-[160,inf) </a> <a href="89413?version=1&table=AcceptanceSR-SF-0J-[100,120)forC1C1WWgrid">SR-SF-0J-[100,120) </a> <a href="89413?version=1&table=AcceptanceSR-SF-0J-[120,160)forC1C1WWgrid">SR-SF-0J-[120,160) </a> <a href="89413?version=1&table=AcceptanceSR-SF-0J-[100,105)forC1C1WWgrid">SR-SF-0J-[100,105) </a> <a href="89413?version=1&table=AcceptanceSR-SF-0J-[105,110)forC1C1WWgrid">SR-SF-0J-[105,110) </a> <a href="89413?version=1&table=AcceptanceSR-SF-0J-[110,120)forC1C1WWgrid">SR-SF-0J-[110,120) </a> <a href="89413?version=1&table=AcceptanceSR-SF-0J-[120,140)forC1C1WWgrid">SR-SF-0J-[120,140) </a> <a href="89413?version=1&table=AcceptanceSR-SF-0J-[140,160)forC1C1WWgrid">SR-SF-0J-[140,160) </a> <a href="89413?version=1&table=AcceptanceSR-SF-0J-[160,180)forC1C1WWgrid">SR-SF-0J-[160,180) </a> <a href="89413?version=1&table=AcceptanceSR-SF-0J-[180,220)forC1C1WWgrid">SR-SF-0J-[180,220) </a> <a href="89413?version=1&table=AcceptanceSR-SF-0J-[220,260)forC1C1WWgrid">SR-SF-0J-[220,260) </a> <a href="89413?version=1&table=AcceptanceSR-SF-0J-[260,inf)forC1C1WWgrid">SR-SF-0J-[260,inf) </a><br/> <a href="89413?version=1&table=AcceptanceSR-SF-1J-[100,inf)forC1C1WWgrid">SR-SF-1J-[100,inf) </a> <a href="89413?version=1&table=AcceptanceSR-SF-1J-[160,inf)forC1C1WWgrid">SR-SF-1J-[160,inf) </a> <a href="89413?version=1&table=AcceptanceSR-SF-1J-[100,120)forC1C1WWgrid">SR-SF-1J-[100,120) </a> <a href="89413?version=1&table=AcceptanceSR-SF-1J-[120,160)forC1C1WWgrid">SR-SF-1J-[120,160) </a> <a href="89413?version=1&table=AcceptanceSR-SF-1J-[100,105)forC1C1WWgrid">SR-SF-1J-[100,105) </a> <a href="89413?version=1&table=AcceptanceSR-SF-1J-[105,110)forC1C1WWgrid">SR-SF-1J-[105,110) </a> <a href="89413?version=1&table=AcceptanceSR-SF-1J-[110,120)forC1C1WWgrid">SR-SF-1J-[110,120) </a> <a href="89413?version=1&table=AcceptanceSR-SF-1J-[120,140)forC1C1WWgrid">SR-SF-1J-[120,140) </a> <a href="89413?version=1&table=AcceptanceSR-SF-1J-[140,160)forC1C1WWgrid">SR-SF-1J-[140,160) </a> <a href="89413?version=1&table=AcceptanceSR-SF-1J-[160,180)forC1C1WWgrid">SR-SF-1J-[160,180) </a> <a href="89413?version=1&table=AcceptanceSR-SF-1J-[180,220)forC1C1WWgrid">SR-SF-1J-[180,220) </a> <a href="89413?version=1&table=AcceptanceSR-SF-1J-[220,260)forC1C1WWgrid">SR-SF-1J-[220,260) </a> <a href="89413?version=1&table=AcceptanceSR-SF-1J-[260,inf)forC1C1WWgrid">SR-SF-1J-[260,inf) </a><br/> <li> <b>Efficiency</b> <br/> <a href="89413?version=1&table=EfficiencySR-DF-0J-[100,inf)forC1C1WWgrid">SR-DF-0J-[100,inf) </a> <a href="89413?version=1&table=EfficiencySR-DF-0J-[160,inf)forC1C1WWgrid">SR-DF-0J-[160,inf) </a> <a href="89413?version=1&table=EfficiencySR-DF-0J-[100,120)forC1C1WWgrid">SR-DF-0J-[100,120) </a> <a href="89413?version=1&table=EfficiencySR-DF-0J-[120,160)forC1C1WWgrid">SR-DF-0J-[120,160) </a> <a href="89413?version=1&table=EfficiencySR-DF-0J-[100,105)forC1C1WWgrid">SR-DF-0J-[100,105) </a> <a href="89413?version=1&table=EfficiencySR-DF-0J-[105,110)forC1C1WWgrid">SR-DF-0J-[105,110) </a> <a href="89413?version=1&table=EfficiencySR-DF-0J-[110,120)forC1C1WWgrid">SR-DF-0J-[110,120) </a> <a href="89413?version=1&table=EfficiencySR-DF-0J-[120,140)forC1C1WWgrid">SR-DF-0J-[120,140) </a> <a href="89413?version=1&table=EfficiencySR-DF-0J-[140,160)forC1C1WWgrid">SR-DF-0J-[140,160) </a> <a href="89413?version=1&table=EfficiencySR-DF-0J-[160,180)forC1C1WWgrid">SR-DF-0J-[160,180) </a> <a href="89413?version=1&table=EfficiencySR-DF-0J-[180,220)forC1C1WWgrid">SR-DF-0J-[180,220) </a> <a href="89413?version=1&table=EfficiencySR-DF-0J-[220,260)forC1C1WWgrid">SR-DF-0J-[220,260) </a> <a href="89413?version=1&table=EfficiencySR-DF-0J-[260,inf)forC1C1WWgrid">SR-DF-0J-[260,inf) </a><br/> <a href="89413?version=1&table=EfficiencySR-DF-1J-[100,inf)forC1C1WWgrid">SR-DF-1J-[100,inf) </a> <a href="89413?version=1&table=EfficiencySR-DF-1J-[160,inf)forC1C1WWgrid">SR-DF-1J-[160,inf) </a> <a href="89413?version=1&table=EfficiencySR-DF-1J-[100,120)forC1C1WWgrid">SR-DF-1J-[100,120) </a> <a href="89413?version=1&table=EfficiencySR-DF-1J-[120,160)forC1C1WWgrid">SR-DF-1J-[120,160) </a> <a href="89413?version=1&table=EfficiencySR-DF-1J-[100,105)forC1C1WWgrid">SR-DF-1J-[100,105) </a> <a href="89413?version=1&table=EfficiencySR-DF-1J-[105,110)forC1C1WWgrid">SR-DF-1J-[105,110) </a> <a href="89413?version=1&table=EfficiencySR-DF-1J-[110,120)forC1C1WWgrid">SR-DF-1J-[110,120) </a> <a href="89413?version=1&table=EfficiencySR-DF-1J-[120,140)forC1C1WWgrid">SR-DF-1J-[120,140) </a> <a href="89413?version=1&table=EfficiencySR-DF-1J-[140,160)forC1C1WWgrid">SR-DF-1J-[140,160) </a> <a href="89413?version=1&table=EfficiencySR-DF-1J-[160,180)forC1C1WWgrid">SR-DF-1J-[160,180) </a> <a href="89413?version=1&table=EfficiencySR-DF-1J-[180,220)forC1C1WWgrid">SR-DF-1J-[180,220) </a> <a href="89413?version=1&table=EfficiencySR-DF-1J-[220,260)forC1C1WWgrid">SR-DF-1J-[220,260) </a> <a href="89413?version=1&table=EfficiencySR-DF-1J-[260,inf)forC1C1WWgrid">SR-DF-1J-[260,inf) </a><br/> <a href="89413?version=1&table=EfficiencySR-SF-0J-[100,inf)forC1C1WWgrid">SR-SF-0J-[100,inf) </a> <a href="89413?version=1&table=EfficiencySR-SF-0J-[160,inf)forC1C1WWgrid">SR-SF-0J-[160,inf) </a> <a href="89413?version=1&table=EfficiencySR-SF-0J-[100,120)forC1C1WWgrid">SR-SF-0J-[100,120) </a> <a href="89413?version=1&table=EfficiencySR-SF-0J-[120,160)forC1C1WWgrid">SR-SF-0J-[120,160) </a> <a href="89413?version=1&table=EfficiencySR-SF-0J-[100,105)forC1C1WWgrid">SR-SF-0J-[100,105) </a> <a href="89413?version=1&table=EfficiencySR-SF-0J-[105,110)forC1C1WWgrid">SR-SF-0J-[105,110) </a> <a href="89413?version=1&table=EfficiencySR-SF-0J-[110,120)forC1C1WWgrid">SR-SF-0J-[110,120) </a> <a href="89413?version=1&table=EfficiencySR-SF-0J-[120,140)forC1C1WWgrid">SR-SF-0J-[120,140) </a> <a href="89413?version=1&table=EfficiencySR-SF-0J-[140,160)forC1C1WWgrid">SR-SF-0J-[140,160) </a> <a href="89413?version=1&table=EfficiencySR-SF-0J-[160,180)forC1C1WWgrid">SR-SF-0J-[160,180) </a> <a href="89413?version=1&table=EfficiencySR-SF-0J-[180,220)forC1C1WWgrid">SR-SF-0J-[180,220) </a> <a href="89413?version=1&table=EfficiencySR-SF-0J-[220,260)forC1C1WWgrid">SR-SF-0J-[220,260) </a> <a href="89413?version=1&table=EfficiencySR-SF-0J-[260,inf)forC1C1WWgrid">SR-SF-0J-[260,inf) </a><br/> <a href="89413?version=1&table=EfficiencySR-SF-1J-[100,inf)forC1C1WWgrid">SR-SF-1J-[100,inf) </a> <a href="89413?version=1&table=EfficiencySR-SF-1J-[160,inf)forC1C1WWgrid">SR-SF-1J-[160,inf) </a> <a href="89413?version=1&table=EfficiencySR-SF-1J-[100,120)forC1C1WWgrid">SR-SF-1J-[100,120) </a> <a href="89413?version=1&table=EfficiencySR-SF-1J-[120,160)forC1C1WWgrid">SR-SF-1J-[120,160) </a> <a href="89413?version=1&table=EfficiencySR-SF-1J-[100,105)forC1C1WWgrid">SR-SF-1J-[100,105) </a> <a href="89413?version=1&table=EfficiencySR-SF-1J-[105,110)forC1C1WWgrid">SR-SF-1J-[105,110) </a> <a href="89413?version=1&table=EfficiencySR-SF-1J-[110,120)forC1C1WWgrid">SR-SF-1J-[110,120) </a> <a href="89413?version=1&table=EfficiencySR-SF-1J-[120,140)forC1C1WWgrid">SR-SF-1J-[120,140) </a> <a href="89413?version=1&table=EfficiencySR-SF-1J-[140,160)forC1C1WWgrid">SR-SF-1J-[140,160) </a> <a href="89413?version=1&table=EfficiencySR-SF-1J-[160,180)forC1C1WWgrid">SR-SF-1J-[160,180) </a> <a href="89413?version=1&table=EfficiencySR-SF-1J-[180,220)forC1C1WWgrid">SR-SF-1J-[180,220) </a> <a href="89413?version=1&table=EfficiencySR-SF-1J-[220,260)forC1C1WWgrid">SR-SF-1J-[220,260) </a> <a href="89413?version=1&table=EfficiencySR-SF-1J-[260,inf)forC1C1WWgrid">SR-SF-1J-[260,inf) </a><br/> </ul> <b>Cutflow:</b> <ul> <li><a href="89413?version=1&table=Cutflow1">Cutflow for direct chargino-pair production via W decay $m(\tilde{\chi}^{\pm}_1,\tilde{\chi}^{0}_1)=(300,50) GeV$</a> <li><a href="89413?version=1&table=Cutflow1">Cutflow for direct chargino-pair production via slepton decay $m(\tilde{\chi}^{\pm}_1,\tilde{l},\tilde{\chi}^{0}_1)=(600,300,1) GeV$</a> <li><a href="89413?version=1&table=Cutflow1">Cutflow for direct slepton-pair production $m(\tilde{l},\tilde{\chi}^{0}_1)=(400,200) GeV$</a> </ul> <b>Truth Code snippets</b> are available under "Resources" (purple button on the left)
Observed events and predicted background yields from the fit for the CRs. For backgrounds whose normalisation is extracted from the fit, the yield expected from the simulation before the fit is also reported. The background denoted as "Other" in the Table includes the non-dominant background sources for this analysis, i.e. Z+jets, $t\bar t$ +V, Higgs and Drell-Yan events. A "–" symbol indicates that the background contribution is negligible.
Distributions of $m_{T2}$ in VR-top-low for data and the estimated SM backgrounds. The normalisation factors extracted from the corresponding CRs are used to rescale the $t\bar t$, single top, WW, WZ and ZZ backgrounds. The fake and non-prompt leptons background (FNP) is calculated using the data-driven matrix method. The uncertainty band includes all sources of systematic and statistical errors and the last bin includes the overflow.
A search for non-resonant Higgs boson pair production, as predicted by the Standard Model, is presented, where one of the Higgs bosons decays via the $H\rightarrow bb$ channel and the other via one of the $H \rightarrow WW^*/ZZ^*/\tau\tau$ channels. The analysis selection requires events to have at least two $b$-tagged jets and exactly two leptons (electrons or muons) with opposite electric charge in the final state. Candidate events consistent with Higgs boson pair production are selected using a multi-class neural network discriminant. The analysis uses 139 fb$^{-1}$ of $pp$ collision data recorded at a centre-of-mass energy of 13 TeV, by the ATLAS detector at the Large Hadron Collider. An observed (expected) upper limit of 1.2 ($0.9^{+0.4}_{-0.3}$) pb is set on the non-resonant Higgs boson pair production cross-section at 95% confidence level, which is equivalent to 40 ($29^{+14}_{-9}$) times the value predicted in the Standard Model.
Reconstruction-level analysis selection efficiency for the $HH \rightarrow bbWW^* \rightarrow bbl\nu l\nu$ signal process as a function of the truth-level $HH$ invariant mass, $m_{HH}$. Each color indicates an additional selection applied sequentially and in the order indicated in the legend with respect to the starting sample of events satisfying the analysis preselection requirements and having at least two $b$-tagged jets. In the legend, ``Trigger'' refers to enforcing the analysis' trigger requirements. For reference, overlaid in grey colour and with arbitrary normalisation is the truth level $m_{HH}$ distribution for events having only the preselection criteria applied. The total efficiency for the tightest selection that is shown (red line), which has selection requirements similar to those of the analysis' signal regions SR-SF and SR-DF, is $7.1\%$.
Expected and observed $95\%$ CL limits on the cross-section of ggF non-resonant Higgs boson pair production as a function of the Higgs boson self-coupling modifier, $\kappa_{\lambda} = \lambda_{HHH} / \lambda_{HHH}^{\textit{SM}}$. The $\pm 1 \sigma$ and $\pm 2 \sigma$ variations about the expected limit, due to statistical and systematic uncertainties, are also shown. The method used for producing estimates of $HH$ production at non-SM values of $\kappa_{\lambda}$ is fully described in arXiv:1906.02025. The theory prediction curve represents the scenario where all parameters and couplings are set to their SM values except for $\kappa_{\lambda}$, also described in arXiv:1906.02025. The uncertainty band on the theory prediction indicates the theoretical uncertainty of this prediction. No additional analysis optimisation relative to that appearing in the main body of the analysis is performed to become particularly sensitive to non-SM values of $\kappa_{\lambda}$. The vertical dashed line indicates the SM scenario with $\kappa_{\lambda} = 1$.
The result of a search for the pair production of the lightest supersymmetric partner of the bottom quark ($\tilde{b}_{1}$) using 139 fb$^{-1}$ of proton-proton data collected at $\sqrt{s} = 13$ TeV by the ATLAS detector is reported. In the supersymmetric scenarios considered both of the bottom-squarks decay into a $b$-quark and the second-lightest neutralino, $\tilde{b}_{1} \rightarrow b + \tilde{\chi}^{0}_{2}$. Each $\tilde{\chi}^{0}_{2}$ is assumed to subsequently decay with 100% branching ratio into a Higgs boson ($h$) like the one in the Standard Model and the lightest neutralino: $\tilde{\chi}^{0}_{2} \rightarrow h + \tilde{\chi}^{0}_{1}$. The $\tilde{\chi}^{0}_{1}$ is assumed to be the lightest supersymmetric particle (LSP) and is stable. Two signal mass configurations are targeted: the first has a constant LSP mass of 60 GeV; and the second has a constant mass difference between the $\tilde{\chi}^{0}_{2}$ and $\tilde{\chi}^{0}_{1}$ of 130 GeV. The final states considered contain no charged leptons, three or more $b$-jets, and large missing transverse momentum. No significant excess of events over the Standard Model background expectation is observed in any of the signal regions considered. Limits at the 95% confidence level are placed in the supersymmetric models considered, and bottom-squarks with mass up to 1.5 TeV are excluded.
Signal acceptance in SRA_H_dm130 for simplified models with $\widetilde{b}\widetilde{b}$ $\rightarrow$ $b\bar{b} \widetilde{\chi}_2^0 \widetilde{\chi}_2^0$ $\rightarrow$ hh$\widetilde{\chi}_1^0 \widetilde{\chi}_1^0$, h $\rightarrow$ $b\bar{b}$ production
Signal acceptance in SRA_H_m60 for simplified models with $\widetilde{b}\widetilde{b}$ $\rightarrow$ $b\bar{b} \widetilde{\chi}_2^0 \widetilde{\chi}_2^0$ $\rightarrow$ hh$\widetilde{\chi}_1^0 \widetilde{\chi}_1^0$, h $\rightarrow$ $b\bar{b}$ production
Signal acceptance in SRA_L_dm130 for simplified models with $\widetilde{b}\widetilde{b}$ $\rightarrow$ $b\bar{b} \widetilde{\chi}_2^0 \widetilde{\chi}_2^0$ $\rightarrow$ hh$\widetilde{\chi}_1^0 \widetilde{\chi}_1^0$, h $\rightarrow$ $b\bar{b}$ production
Measurements of $K_S^0$ and $\Lambda^0$ production in $t\bar{t}$ final states have been performed. They are based on a data sample with integrated luminosity of 4.6 $\mathrm{fb}^{-1}$ from proton-proton collisions at a centre-of-mass energy of 7 TeV, collected in 2011 with the ATLAS detector at the Large Hadron Collider. Neutral strange particles are separated into three classes, depending on whether they are contained in a jet, with or without a $b$-tag, or not associated with a selected jet. The aim is to look for differences in their main kinematic distributions. A comparison of data with several Monte Carlo simulations using different hadronisation and fragmentation schemes, colour reconnection models and different tunes for the underlying event has been made. The production of neutral strange particles in $t\bar{t}$ dileptonic events is found to be well described by current Monte Carlo models for $K_S^0$ and $\Lambda^0$ production within jets, but not for those produced outside jets.
The transverse momentum ($p_{T}$) distribution for $K^{0}_{S}$ production inside $b$-jets for unfolded data to particle level, normalised to the total number of top pair dileptonic events and scaled to the bin width. The systematic uncertainties are, in order, due to; the MC modelling, the tracking inefficiencies, the jet energy scale (JES), the jet energy resolution (JER), out-of-fiducial events and the unfolding non-closure.
The energy fraction ($x_{K}$) distribution for $K^{0}_{S}$ production inside $b$-jets for unfolded data to particle level, normalised to the total number of top pair dileptonic events and scaled to the bin width. The systematic uncertainties are, in order, due to; the MC modelling, the tracking ineficiencies, the jet energy scale (JES), the jet energy resolution (JER), out-of-fiducial events and the unfolding non-closure.
The energy distribution for $K^{0}_{S}$ production inside $b$-jets for unfolded data to particle level, normalised to the total number of top pair dileptonic events and scaled to the bin width. The systematic uncertainties are, in order, due to; the MC modelling, the tracking ineficiencies, the jet energy scale (JES), the jet energy resolution (JER), out-of-fiducial events and the unfolding non-closure.
A measurement of $W^\pm$ boson production in lead-lead collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV is reported using data recorded by the ATLAS experiment at the LHC in 2015, corresponding to a total integrated luminosity of $0.49\;\mathrm{nb^{-1}}$. The $W^\pm$ bosons are reconstructed in the electron or muon leptonic decay channels. Production yields of leptonically decaying $W^\pm$ bosons, normalised by the total number of minimum-bias events and the nuclear thickness function, are measured within a fiducial region defined by the detector acceptance and the main kinematic requirements. These normalised yields are measured separately for $W^+$ and $W^-$ bosons, and are presented as a function of the absolute value of pseudorapidity of the charged lepton and of the collision centrality. The lepton charge asymmetry is also measured as a function of the absolute value of lepton pseudorapidity. In addition, nuclear modification factors are calculated using the $W^\pm$ boson production cross-sections measured in $pp$ collisions. The results are compared with predictions based on next-to-leading-order calculations with CT14 parton distribution functions as well as with predictions obtained with the EPPS16 and nCTEQ15 nuclear parton distribution functions. No dependence of normalised production yields on centrality and a good agreement with predictions are observed for mid-central and central collisions. For peripheral collisions, the data agree with predictions within 1.7 (0.9) standard deviations for $W^-$ ($W^+$) bosons.
The covariance matrix of the differential normalised production yields for $W^+$ bosons. Systematic uncertainties related to $T_{\mathrm{AA}}$ (1.6%) are not included.
The covariance matrix of the differential normalised production yields for $W^-$ bosons. Systematic uncertainties related to $T_{\mathrm{AA}}$ (1.6%) are not included.
The covariance matrix of the lepton charge asymmetry.
A search for long-lived particles decaying into an oppositely charged lepton pair, $\mu\mu$, $ee$, or $e\mu$, is presented using 32.8 fb$^{-1}$ of $pp$ collision data collected at $\sqrt{s}$ = 13 TeV by the ATLAS detector at the LHC. Candidate leptons are required to form a vertex, within the inner tracking volume of ATLAS, displaced from the primary $pp$ interaction region. No lepton pairs with an invariant mass greater than 12 GeV are observed, consistent with the background expectations derived from data. The result is interpreted in a supersymmetric model in which the lightest neutralino, produced via squark-antisquark production, decays into $\ell^{+}\ell^{'-}\nu$ ($\ell$, $\ell^{'} = e$, $\mu$) with a finite lifetime due to the presence of R-parity violating couplings. Cross-section limits are presented for specific squark and neutralino masses. For a 700 GeV squark, neutralinos with masses of 50-500 GeV and mean proper lifetimes corresponding to $c\tau$ values between 1 mm to 6 m are excluded. For a 1.6 TeV squark, $c\tau$ values between 3 mm to 1 m are excluded for 1.3 TeV neutralinos.
dRcos distribution of dimuon pairs (scaled) and dimuon vertices in the cosmic rays control region. The distribution of all dimuon pairs is scaled to the DV distribution.
Dependence of the overall signal efficiency on the transverse decay radius Rxy of the long-lived Z' for Z' -> ee. The error bars indicate the total uncertainties.
Dependence of the overall signal efficiency on the pT of the long-lived Z' for Z' -> ee. The error bars indicate the total uncertainties.
The inclusive cross-section for jet production in association with a Z boson decaying into an electron-positron pair is measured as a function of the transverse momentum and the absolute rapidity of jets using 19.9 fb$^{-1}$ of $\sqrt s = 8$ TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. The measured Z + jets cross-section is unfolded to the particle level. The cross-section is compared with state-of-the-art Standard Model calculations, including the next-to-leading-order and next-to-next-to-leading-order perturbative QCD calculations, corrected for non-perturbative and QED radiation effects. The results of the measurements cover final-state jets with transverse momenta up to 1 TeV, and show good agreement with fixed-order calculations.
List of experimentally considered systematic uncertainties for the Z + jets cross-section measurement
The double-differential Z + jets production cross-section as a function of |y_{jet}| in the 25 GeV < p_{T}^{jet} < 50 GeV range. The particle level phase space definition: - 66 GeV < m_{ee} < 116 GeV - |eta_{electron}| < 2.47 - p_{T}^{electron} > 20 GeV - anti-kt R=0.4 jets N>=1 - |y_{jet}| < 3.4 - p_{T}^{jet} > 25 GeV - Delta R(jet, electron) > 0.4
The double-differential Z + jets production cross-section as a function of |y_{jet}| in the 50 GeV < p_{T}^{jet} < 100 GeV range. The particle level phase space definition: - 66 GeV < m_{ee} < 116 GeV - |eta_{electron}| < 2.47 - p_{T}^{electron} > 20 GeV - anti-kt R=0.4 jets N>=1 - |y_{jet}| < 3.4 - p_{T}^{jet} > 25 GeV - Delta R(jet, electron) > 0.4
Narrow resonances decaying into $WW$, $WZ$ or $ZZ$ boson pairs are searched for in 139 fb$^{-1}$ of proton-proton collision data at a centre-of-mass energy of $\sqrt{s}=13$ TeV recorded with the ATLAS detector at the Large Hadron Collider from 2015 to 2018. The diboson system is reconstructed using pairs of high transverse momentum, large-radius jets. These jets are built from a combination of calorimeter- and tracker-inputs compatible with the hadronic decay of a boosted $W$ or $Z$ boson, using jet mass and substructure properties. The search is performed for diboson resonances with masses greater than 1.3 TeV. No significant deviations from the background expectations are observed. Exclusion limits at the 95% confidence level are set on the production cross-section times branching ratio into dibosons for resonances in a range of theories beyond the Standard Model, with the highest excluded mass of a new gauge boson at 3.8 TeV in the context of mass-degenerate resonances that couple predominantly to gauge bosons.
Limit Plot
HVT WW Acceptance times Efficiency
Limit Plot
A search for a heavy charged-boson resonance decaying into a charged lepton (electron or muon) and a neutrino is reported. A data sample of 139 fb$^{-1}$ of proton-proton collisions at $\sqrt{s} = 13$ TeV collected with the ATLAS detector at the LHC during 2015-2018 is used in the search. The observed transverse mass distribution computed from the lepton and missing transverse momenta is consistent with the distribution expected from the Standard Model, and upper limits on the cross section for $pp \to W^\prime \to \ell\nu$ are extracted ($\ell = e$ or $\mu$). These vary between 1.3 pb and 0.05 fb depending on the resonance mass in the range between 0.15 and 7.0 TeV at 95% confidence level for the electron and muon channels combined. Gauge bosons with a mass below 6.0 TeV and 5.1 TeV are excluded in the electron and muon channels, respectively, in a model with a resonance that has couplings to fermions identical to those of the Standard Model $W$ boson. Cross-section limits are also provided for resonances with several fixed $\Gamma / m$ values in the range between 1% and 15%. Model-independent limits are derived in single-bin signal regions defined by a varying minimum transverse mass threshold. The resulting visible cross-section upper limits range between 4.6 (15) pb and 22 (22) ab as the threshold increases from 130 (110) GeV to 5.1 (5.1) TeV in the electron (muon) channel.
Transverse mass distribution for events satisfying all selection criteria in the electron channel.
Transverse mass distribution for events satisfying all selection criteria in the muon channel.
Upper limits at the 95% CL on the cross section for SSM $W^\prime$ production and decay to the electron+neutrino channel as a function of the $W^\prime$ pole mass.