@article{OPUS4-22690, title = {Search for diboson resonances in hadronic final states in 139 fb\(^{-1}\) of \(pp\) collisions at √\(s\)=13 TeV with the ATLAS detector}, series = {Journal of High Energy Physics}, volume = {09}, journal = {Journal of High Energy Physics}, number = {91}, organization = {The ATLAS Collaboration}, doi = {10.1007/JHEP09(2019)091}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226905}, pages = {1-42}, year = {2019}, abstract = {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 root s = 13TeV 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 1.3TeV. 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 3.8TeV in the context of mass-degenerate resonances that couple predominantly to gauge bosons.}, language = {en} } @article{OPUS4-22678, title = {Search for \({WW/WZ}\) resonance production in \(lvqq\) final states in \(pp\) collisions at root \(s\)=13 TeV with the ATLAS detector}, series = {Journal of High Energy Physics}, volume = {42}, journal = {Journal of High Energy Physics}, organization = {The ATLAS Collaboration}, doi = {10.1007/JHEP03(2018)042}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226787}, pages = {1-44}, year = {2018}, abstract = {A search is conducted for new resonances decaying into a WW or WZ boson pair, where one W boson decays leptonically and the other W or Z boson decays hadronically. It is based on proton-proton collision data with an integrated luminosity of 36.1 fb(-1) collected with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of root s = 13 TeV in 2015 and 2016. The search is sensitive to diboson resonance production via vector-boson fusion as well as quark-antiquark annihilation and gluon-gluon fusion mechanisms. No significant excess of events is observed with respect to the Standard Model backgrounds. Several benchmark models are used to interpret the results. Limits on the production cross section are set for a new narrow scalar resonance, a new heavy vector-boson and a spin-2 Kaluza-Klein graviton.}, language = {en} } @article{OPUS4-22675, title = {Search for supersymmetry in final states with charm jets and missing transverse momentum in 13 TeV \(pp\) collisions with the ATLAS detector}, series = {Journal of High Energy Physics}, volume = {09}, journal = {Journal of High Energy Physics}, organization = {The ATLAS Collaboration}, doi = {10.1007/JHEP09(2018)050}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226752}, pages = {1-43}, year = {2018}, abstract = {A search for supersymmetric partners of top quarks decaying as (t) over tilde (1) -> c (chi) over tilde (0)(1)and supersymmetric partners of charm quarks decaying as (c) over tilde (1) -> c (chi) over tilde (0)(1) where (chi) over tilde (0)(1) is the lightest neutralino, is presented. The search uses 36.1 fb(-1) pp collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS experiment at the Large Hadron Collider and is performed in final states with jets identified as containing charm hadrons. Assuming a 100\% branching ratio to c (chi) over tilde (0)(1), top and charm squarks with masses up to 850 GeV are excluded at 95\% confidence level for a massless lightest neutralino. For m (t) over tilde (1,(c) over tilde1) - m((chi) over tilde 10)< 100 GeV, top and charm squark masses up to 500 GeV are excluded.}, language = {en} } @article{OPUS4-22602, title = {Measurements of differential cross sections of top quark pair production in association with jets in pp collisions at root s=13 TeV using the ATLAS detector}, series = {Journal of High Energy Physics}, volume = {159}, journal = {Journal of High Energy Physics}, number = {10}, organization = {The ATLAS Collaboration}, doi = {10.1007/JHEP10(2018)159}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226023}, pages = {1-57}, year = {2018}, abstract = {Measurements of di ff erential cross sections of top quark pair production in association with jets by the ATLAS experiment at the LHC are presented. The measurements are performed as functions of the top quark transverse momentum, the transverse momentum of the top quark-antitop quark system and the out-of-plane transverse momentum using data from pp collisions at p s = 13TeV collected by the ATLAS detector at the LHC in 2015 and corresponding to an integrated luminosity of 3.2 fb. The top quark pair events are selected in the lepton (electron or muon) + jets channel. The measured cross sections, which are compared to several predictions, allow a detailed study of top quark production.}, language = {en} } @article{OPUS4-22611, title = {Search for flavour-changing neutral current top-quark decays \(t\) -> \({qZ}\) in proton-proton collisions at root s=13 TeV with the ATLAS detector}, series = {Journal of High Energy Physics}, volume = {176}, journal = {Journal of High Energy Physics}, number = {7}, organization = {The ATLAS Collaboration}, doi = {10.1007/JHEP07(2018)176}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226114}, pages = {1-40}, year = {2018}, abstract = {A search for flavour-changing neutral-current processes in top-quark decays is presented. Data collected with the ATLAS detector from proton-proton collisions at the Large Hadron Collider at a centre-of-mass energy of root s = 13TeV, corresponding to an integrated luminosity of 36.1 fb(-1), are analysed. The search is performed using top-quark pair events, with one top quark decaying through the t -> qZ (q = u, c) flavour-changing neutral-current channel, and the other through the dominant Standard Model mode t -> bW. Only Z boson decays into charged leptons and leptonic W boson decays are considered as signal. Consequently, the final-state topology is characterized by the presence of three isolated charged leptons (electrons or muons), at least two jets, one of the jets originating from a b-quark, and missing transverse momentum from the undetected neutrino. The data are consistent with Standard Model background contributions, and at 95\% confidence level the search sets observed (expected) upper limits of 1.7 x 10(-4) (2.4 x 10(-4)) on the t -> uZ branching ratio and 2.4 x 10(-4) (3.2 x 10(-4)) on the t -> cZ branching ratio, constituting the most stringent limits to date.}, language = {en} } @article{OPUS4-22613, title = {Search for pair production of up-type vector-like quarks and for four-top-quark events in final states with multiple \(b\)-jets with the ATLAS detector}, series = {Journal of High Energy Physics}, volume = {89}, journal = {Journal of High Energy Physics}, number = {7}, organization = {The ATLAS Collaboration}, doi = {10.1007/JHEP07(2018)089}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226131}, pages = {1-67}, year = {2018}, abstract = {A search for pair production of up-type vector-like quarks (T) with a significant branching ratio into a top quark and either a Standard Model Higgs boson or a Z boson is presented. The same analysis is also used to search for four-top-quark production in several new physics scenarios. The search is based on a dataset of pp collisions at root s = 13TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider and corresponds to an integrated luminosity of 36.1 fb(-1). Data are analysed in the lepton+jets final state, characterised by an isolated electron or muon with high transverse momentum, large missing transverse momentum and multiple jets, as well as the jets+E-T(miss) final state, characterised by multiple jets and large missing transverse momentum. The search exploits the high multiplicity of jets identified as originating from b-quarks, and the presence of boosted, hadronically decaying top quarks and Higgs bosons reconstructed as large-radius jets, characteristic of signal events. No significant excess above the Standard Model expectation is observed, and 95\% CL upper limits are set on the production cross sections for the different signal processes considered. These cross-section limits are used to derive lower limits on the mass of a vector-like T quark under several branching ratio hypotheses assuming contributions from T -> Wb, Zt, Ht decays. The 95\% CL observed lower limits on the T quark mass range between 0.99TeV and 1.43TeV for all possible values of the branching ratios into the three decay modes considered, significantly extending the reach beyond that of previous searches. Additionally, upper limits on anomalous four-top-quark production are set in the context of an effective field theory model, as well as in an universal extra dimensions model.}, language = {en} } @article{OPUS4-22600, title = {Search for pair production of Higgs bosons in the \({bb̅bb̅}\) final state using proton-proton collisions at root s=13 TeV with the ATLAS detector}, series = {Journal of High Energy Physics}, volume = {30}, journal = {Journal of High Energy Physics}, organization = {The ATLAS Collaboration}, doi = {10.1007/JHEP01(2019)030}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226001}, pages = {1-48}, year = {2018}, abstract = {A search for Higgs boson pair production in the bbbb final state is carried out with up to 36.1 fb(-1) of LHC proton-proton collision data collected at s=13 TeV with the ATLAS detector in 2015 and 2016. Three benchmark signals are studied: a spin-2 graviton decaying into a Higgs boson pair, a scalar resonance decaying into a Higgs boson pair, and Standard Model non-resonant Higgs boson pair production. Two analyses are carried out, each implementing a particular technique for the event reconstruction that targets Higgs bosons reconstructed as pairs of jets or single boosted jets. The resonance mass range covered is 260-3000 GeV. The analyses are statistically combined and upper limits on the production cross section of Higgs boson pairs times branching ratio to bbbb are set in each model. No significant excess is observed; the largest deviation of data over prediction is found at a mass of 280 GeV, corresponding to 2.3 standard deviations globally. The observed 95\% confidence level upper limit on the non-resonant production is 13 times the Standard Model prediction.}, language = {en} } @article{OPUS4-22595, title = {Searches for heavy \({ZZ}\) and \({ZW}\) resonances in the \({llqq}\) and \({vvqq}\) final states in \({pp}\) collisions at root s=13 TeV with the ATLAS detector}, series = {Journal of High Energy Physics}, volume = {9}, journal = {Journal of High Energy Physics}, organization = {The ATLAS Collaboration}, doi = {10.1007/JHEP03(2018)009}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-225951}, pages = {1-52}, year = {2018}, abstract = {This paper reports searches for heavy resonances decaying into ZZ or ZW using data from proton-proton collisions at a centre-of-mass energy of root s - 13 TeV. The data, corresponding to an integrated luminosity of 36.1 fb(-1), were recorded with the ATLAS detector in 2015 and 2016 at the Large Hadron Collider. The searches are performed in final states in which one Z boson decays into either a pair of light charged leptons (electrons and muons) or a pair of neutrinos, and the associated W boson or the other Z boson decays hadronically. No evidence of the production of heavy resonances is observed. Upper bounds on the production cross sections of heavy resonances times their decay branching ratios to ZZ or ZW are derived in the mass range 300-5000 GeV within the context of Standard Model extensions with additional Higgs bosons, a heavy vector triplet or warped extra dimensions. Production through gluon-gluon fusion, Drell-Yan or vector-boson fusion are considered, depending on the assumed model.}, language = {en} } @article{OPUS4-27753, title = {Search for squarks and gluinos in final states with same-sign leptons and jets using 139 fb\(^{-1}\) of data collected with the ATLAS detector}, series = {Journal of High Energy Physics}, journal = {Journal of High Energy Physics}, number = {6}, organization = {The ATLAS Collaboration}, doi = {10.1007/JHEP06(2020)046}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-277538}, pages = {46}, year = {2020}, abstract = {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 root 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.}, language = {en} } @article{OPUS4-22067, title = {Angular analysis of B-d(0) -> K* µ\(^+\)μ\(^-\) decays in \({pp}\) collisions at root s=8 TeV with the ATLAS detector}, series = {Journal of High Energy Physics}, volume = {47}, journal = {Journal of High Energy Physics}, organization = {The ATLAS collaboration}, doi = {10.1007/JHEP10(2018)047}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-220670}, pages = {1-47}, year = {2018}, abstract = {An angular analysis of the decay B-d(0) -> K*mu(+)mu(-) is presented, based on proton-proton collision data recorded by the ATLAS experiment at the LHC. The study is using 20.3 fb(-1) of integrated luminosity collected during 2012 at centre-of-mass energy of root s = 8TeV. Measurements of the K* longitudinal polarisation fraction and a set of angular parameters obtained for this decay are presented. The results are compatible with the Standard Model predictions.}, language = {en} }