@article{OPUS4-22609, title = {Search for a heavy Higgs boson decaying into a \(Z\) boson and another heavy Higgs boson in the \({llbb}\) final state in \({pp}\) collisions at root \(s\)=13 TeV with the ATLAS detector}, series = {Physics Letters B}, volume = {783}, journal = {Physics Letters B}, organization = {The ATLAS Collaboration}, doi = {10.1016/j.physletb.2018.07.006}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226098}, pages = {392-414}, year = {2018}, abstract = {A search for a heavy neutral Higgs boson, A, decaying into a Z boson and another heavy Higgs boson, H, is performed using a data sample corresponding to an integrated luminosity of 36.1 fb(-1) from proton-proton collisions at root s = 13 TeV recorded in 2015 and 2016 by the ATLAS detector at the Large Hadron Collider. The search considers the Z boson decaying to electrons or muons and the H boson into a pair of b-quarks. No evidence for the production of an A boson is found. Considering each production process separately, the 95\% confidence-level upper limits on the pp -> A -> ZH production cross-section times the branching ratio H -> bb are in the range of 14-830 fb for the gluon-gluon fusion process and 26-570 fb for the b-associated process for the mass ranges 130-700 GeV of the H boson and 230-800 GeV of the A boson. The results are interpreted in the context of two-Higgs-doublet models. (C) 2018 Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).}, language = {en} } @article{OPUS4-22606, title = {Measurement of the Higgs boson mass in the \(H\) -> \({ZZ}\)* -> 4l and \(H\) -> \({γγ}\) channels with root \(s\)=13 TeV \({pp}\) collisions using the ATLAS detector}, series = {Physics Letters B}, volume = {784}, journal = {Physics Letters B}, organization = {The ATLAS Collaboration}, doi = {10.1016/j.physletb.2018.07.050}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226065}, pages = {345-366}, year = {2018}, abstract = {The mass of the Higgs boson is measured in the H -> ZZ* -> 4l and in the H -> gamma gamma decay channels with 36.1 fb(-1) of proton-proton collision data from the Large Hadron Collider at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector in 2015 and 2016. The measured value in the H -> ZZ* -> 4l channel is m(H)(ZZ*) = 124.79 +/- 0.37 GeV, while the measured value in the H -> gamma gamma channel is m(H)(gamma gamma) = 124.93 +/- 0.40 GeV. Combining these results with the ATLAS measurement based on 7 and 8 TeV proton-proton collision data yields a Higgs boson mass of m(H) = 124.97 +/- 0.24 GeV. (c) 2018 The Author. Published by Elsevier B.V.}, language = {en} } @article{OPUS4-22614, title = {Search for Higgs boson decays into pairs of light (pseudo)scalar particles in the \({γγ jj}\) final state in \({pp}\) collisions at root \(s\)=13 TeV with the ATLAS detector}, series = {Physics Letters B}, volume = {782}, journal = {Physics Letters B}, organization = {The ATLAS Collaboration}, doi = {10.1016/j.physletb.2018.06.011}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226147}, pages = {750-767}, year = {2018}, abstract = {This Letter presents a search for exotic decays of the Higgs boson to a pair of new (pseudo) scalar particles, H -> aa, where the a particle has a mass in the range 20-60 GeV, and where one of the a bosons decays into a pair of photons and the other to a pair of gluons. The search is performed in event samples enhanced in vector-boson fusion Higgs boson production by requiring two jets with large invariant mass in addition to the Higgs boson candidate decay products. The analysis is based on the full dataset of pp collisions at root s = 13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider, corresponding to an integrated luminosity of 36.7 fb(-1). The data are in agreement with the Standard Model predictions and an upper limit at the 95\% confidence level is placed on the production cross section times the branching ratio for the decay H -> aa -> gamma gamma gg. This limit ranges from 3.1 pb to 9.0 pb depending on the mass of the a boson. (C) 2018 The Author. Published by Elsevier B.V.}, language = {en} } @article{OPUS4-22654, title = {Search for the standard model Higgs boson produced in association with top quarks and decaying into a b(b)overbar pair in \(pp\) collisions at root \(s\)=13 TeV with the ATLAS detector}, series = {Physical Review D}, volume = {97}, journal = {Physical Review D}, number = {7}, organization = {The ATLAS Collaboration}, doi = {10.1103/PhysRevD.97.072016}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226545}, pages = {1-44}, year = {2018}, abstract = {A search for the standard model Higgs boson produced in association with a top-quark pair, t(t)overbarH, is presented. The analysis uses 36.1 fb(-1) of pp collision data at root s = 13 TeV collected with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The search targets the H -> b(b)overbar decay mode. The selected events contain either one or two electrons or muons from the top-quark decays, and are then categorized according to the number of jets and how likely these are to contain b-hadrons. Multivariate techniques are used to discriminate between signal and background events, the latter being dominated by ft + jets production. For a Higgs boson mass of 125 GeV, the ratio of the measured t(t)overbarH signal cross-section to the standard model expectation is found to be mu = 0.84(-0.61)(+0.64). A value of mu greater than 2.0 is excluded at 95\% confidence level (C.L.) while the expected upper limit is mu < 1.2 in the absence of a t(t)overbarH signal.}, language = {en} } @article{OPUS4-22656, title = {Evidence for the associated production of the Higgs boson and a top quark pair with the ATLAS detector}, series = {Physical Review D}, volume = {97}, journal = {Physical Review D}, organization = {The ATLAS Collaboration}, doi = {10.1103/PhysRevD.97.072003}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226569}, pages = {1-44}, year = {2018}, abstract = {A search for the associated production of the Higgs boson with a top quark pair (tt (b) over barH) is reported. The search is performed in multilepton final states using a data set corresponding to an integrated luminosity of 36.1 fb(-1) of proton-proton collision data recorded by the ATLAS experiment at a center-of-mass energy root s = 13 TeV at the Large Hadron Collider. Higgs boson decays to WW*, tau tau, and ZZ* are targeted. Seven final states, categorized by the number and flavor of charged-lepton candidates, are examined for the presence of the Standard Model Higgs boson with a mass of 125 GeVand a pair of top quarks. An excess of events over the expected background from Standard Model processes is found with an observed significance of 4.1 standard deviations, compared to an expectation of 2.8 standard deviations. The best fit for the (tt (b) over barH) production cross section is sot (tt (b) over barH) = 790(-210)(+230) fb, in agreement with the Standard Model prediction of 507(-50)(+35) fb. The combination of this result with other tt (b) over barH searches from the ATLAS experiment using the Higgs boson decay modes to b (b) over bar, gamma gamma and ZZ* -> 4l, has an observed significance of 4.2 standard deviations, compared to an expectation of 3.8 standard deviations. This provides evidence for the tt (b) over barH production mode.}, language = {en} } @article{OPUS4-22651, title = {Search for photonic signatures of gauge-mediated supersymmetry in 13 TeV \(pp\) collisions with the ATLAS detector}, series = {Physical Review D}, volume = {97}, journal = {Physical Review D}, organization = {The ATLAS Collaboration}, doi = {10.1103/PhysRevD.97.092006}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226510}, pages = {1-32}, year = {2018}, abstract = {A search is presented for photonic signatures, motivated by generalized models of gauge-mediated supersymmetry breaking. This search makes use of proton-proton collision data at root s = 13 TeV corresponding to an integrated luminosity of 36.1 fb(-1) recorded by the ATLAS detector at the LHC, and it explores models dominated by both strong and electroweak production of supersymmetric partner states. Experimental signatures incorporating an isolated photon and significant missing transverse momentum are explored. These signatures include events with an additional photon or additional jet activity not associated with any specific underlying quark flavor. No significant excess of events is observed above the Standard Model prediction, and 95\% confidence-level upper limits of between 0.083 and 0.32 fb are set on the visible cross section of contributions from physics beyond the Standard Model. These results are interpreted in terms of lower limits on the masses of gluinos, squarks, and gauginos in the context of generalized models of gauge-mediated supersymmetry, which reach as high as 2.3 TeV for strongly produced and 1.3 TeV for weakly produced supersymmetric partner pairs.}, language = {en} } @article{OPUS4-22596, title = {Comparison between simulated and observed LHC beam backgrounds in the ATLAS experiment at \(E\)\(_{beam}\)=4 TeV}, series = {Journal of Instrumentation}, volume = {13}, journal = {Journal of Instrumentation}, organization = {The ATLAS Collaboration}, doi = {10.1088/1748-0221/13/12/P12006}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-225966}, pages = {1-40}, year = {2018}, abstract = {Results of dedicated Monte Carlo simulations of beam-induced background (BIB) in the ATLAS experiment at the Large Hadron Collider (LHC) are presented and compared with data recorded in 2012. During normal physics operation this background arises mainly from scattering of the 4 TeV protons on residual gas in the beam pipe. Methods of reconstructing the BIB signals in the ATLAS detector, developed and implemented in the simulation chain based on the FLUKA Monte Carlo simulation package, are described. The interaction rates are determined from the residual gas pressure distribution in the LHC ring in order to set an absolute scale on the predicted rates of BIB so that they can be compared quantitatively with data. Through these comparisons the origins of the BIB leading to different observables in the ATLAS detectors are analysed. The level of agreement between simulation results and BIB measurements by ATLAS in 2012 demonstrates that a good understanding of the origin of BIB has been reached.}, 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{OPUS4-22598, title = {Search for W ' -> \({tb}\) decays in the hadronic final state using \({pp}\) collisions at root s=13 TeV with the ATLAS detector}, series = {Physics Letters B}, volume = {781}, journal = {Physics Letters B}, organization = {The ATLAS Collaboration}, doi = {10.1016/j.physletb.2018.03.036}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-225987}, pages = {327-348}, year = {2018}, abstract = {A search for W'-boson production in the W' -> t (b) over bar -> q (q) over bar 'b (b) over bar decay channel is presented using 36.1 fb(-1) of 13 TeV proton-proton collision data collected by the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The search is interpreted in terms of both a left-handed and a right-handed chiral W' boson within the mass range 1-5 TeV. Identification of the hadronically decaying top quark is performed using jet substructure tagging techniques based on a shower deconstruction algorithm. No significant deviation from the Standard Model prediction is observed and the results are expressed as upper limits on the W' -> t (b) over bar production cross-section times branching ratio as a function of the W'-boson mass. These limits exclude W' bosons with right-handed couplings with masses below 3.0 TeV and W' bosons with left-handed couplings with masses below 2.9 TeV, at the 95\% confidence level. (C) 2018 The Author. Published by Elsevier B.V.}, language = {en} } @article{OPUS4-22604, title = {Search for R-parity-violating supersymmetric particles in multi-jet final states produced in \({p-p}\) collisions at root \(s\)=13 TeV using the ATLAS detector at the LHC}, series = {Physics Letters B}, volume = {785}, journal = {Physics Letters B}, organization = {The ATLAS Collaboration}, doi = {10.1016/j.physletb.2018.08.021}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226047}, pages = {136-158}, year = {2018}, abstract = {Results of a search for gluino pair production with subsequent R-parity-violating decays to quarks are presented. This search uses 36.1 fb(-1) of data collected by the ATLAS detector in proton-proton collisions with a centre-of-mass energy of root s = 13 TeV at the LHC. The analysis is performed using requirements on the number of jets and the number of jets tagged as containing a b-hadron as well as a topological observable formed by the scalar sum of masses of large-radius jets in the event. No significant excess above the expected Standard Model background is observed. Limits are set on the production of gluinos in models with the R-parity-violating decays of either the gluino itself (direct decay) or the neutralino produced in the R-parity-conserving gluino decay (cascade decay). In the gluino cascade decay model, gluino masses below 1850 GeV are excluded for 1000 GeV neutralino mass. For the gluino direct decay model, the 95\% confidence level upper limit on the cross section times branching ratio varies between 0.80 fb at m((g) over tilde) = 900 GeV and 0.011 fb at m((g) over tilde) = 1800 GeV. (c) 2018 The Author. Published by Elsevier B.V. This is an open access article under the CC BY license.}, language = {en} }