TY - JOUR T1 - Search for exclusive Higgs and Z boson decays to phi gamma and rho gamma with the ATLAS detector JF - Journal of High Energy Physics N2 - A search for the exclusive decays of the Higgs and Z bosons to a phi or rho meson and a photon is performed with a pp collision data sample corresponding to an integrated luminosity of up to 35.6 fb(-1) collected at root s = 13 TeV with the ATLAS detector at the CERN Large Hadron Collider. These decays have been suggested as a probe of the Higgs boson couplings to light quarks. No significant excess of events is observed above the background, as expected from the Standard Model. Upper limits at 95% confidence level were obtained on the branching fractions of the Higgs boson decays to phi gamma and rho gamma of 4.8 x 10(-4) and 8.8 x 10(-4), respectively. The corresponding 95% confidence level upper limits for the Z boson decays are 0.9 x 10(-6) and 25 x 10(-6) for phi gamma and rho gamma, respectively. KW - Hadron-Hadron scattering (experiments) KW - Mass KW - Hierarchy KW - QCD KW - Higgs physics Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-220717 VL - 127 IS - 7 ER - TY - JOUR T1 - Search for top-squark pair production in final states with one lepton, jets, and missing transverse momentum using 36 fb\(^{-1}\) of root s=13 TeV \({pp}\) collision data with the ATLAS detector JF - Journal of High Energy Physics N2 - The results of a search for the direct pair production of top squarks, the supersymmetric partner of the top quark, in final states with one isolated electron or muon, several energetic jets, and missing transverse momentum are reported. The analysis also targets spin-0 mediator models, where the mediator decays into a pair of dark-matter particles and is produced in association with a pair of top quarks. The search uses data from proton-proton collisions delivered by the Large Hadron Collider in 2015 and 2016 at a centre-of-mass energy of root s = 13TeV and recorded by the ATLAS detector, corresponding to an integrated luminosity of 36 fb(-1). A wide range of signal scenarios with different mass-splittings between the top squark, the lightest neutralino and possible intermediate supersymmetric particles are considered, including cases where the W bosons or the top quarks produced in the decay chain are off-shell. No significant excess over the Standard Model prediction is observed. The null results are used to set exclusion limits at 95% confidence level in several supersymmetry benchmark models. For pair-produced top-squarks decaying into top quarks, top-squark masses up to 940 GeV are excluded. Stringent exclusion limits are also derived for all other considered top-squark decay scenarios. For the spin-0 mediator models, upper limits are set on the visible cross-section. KW - Hadron-Hadron scattering (experiments) KW - Dark-matter production KW - Symmetry-breaking KW - Plus plus KW - Model KW - Supersymmetry KW - Program KW - LHS KW - Mass KW - Extension KW - Physics Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-220733 VL - 108 IS - 6 ER - TY - JOUR T1 - 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 JF - Journal of High Energy Physics N2 - 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. KW - Beyond Standard Model KW - Hadron-Hadron scattering (experiments) KW - Boson KW - Distributions KW - Combination KW - Hierarchy KW - Mass Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225951 VL - 9 ER - TY - JOUR T1 - Search for W ' -> \({tb}\) decays in the hadronic final state using \({pp}\) collisions at root s=13 TeV with the ATLAS detector JF - Physics Letters B N2 - 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. KW - Symmetry-breaking KW - Pair production KW - ++ KW - Dynamics KW - Physics KW - Mass Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225987 VL - 781 ER - TY - JOUR T1 - Search for heavy \({ZZ}\) resonances in the l\(^+\)l\(^-\)l\(^+\)l\(^-\) and l\(^+\)l\(^-\) nu(nu)over-bar final states using proton-proton collisions at root s=13 TeV with the ATLAS detector JF - The European Physical Journal C N2 - A search for heavy resonances decaying into a pair of Z bosons leading to l(+) l(-) l(+) l(-) and l(+) l(-) nu(nu) over bar final states, where l stands for either an electron or a muon, is presented. The search uses proton-proton collision data at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 36.1 fb(-1) collected with the ATLAS detector during 2015 and 2016 at the Large Hadron Collider. Different mass ranges for the hypothetical resonances are considered, depending on the final state and model. The different ranges span between 200 and 2000 GeV. The results are interpreted as upper limits on the production cross section of a spin-0 or spin-2 resonance. The upper limits for the spin-0 resonance are translated to exclusion contours in the context of Type-I and Type-II two-Higgs-doublet models, while those for the spin-2 resonance are used to constrain the Randall-Sundrum model with an extra dimension giving rise to spin-2 graviton excitations. KW - Boson KW - Decay KW - Mass KW - Distributions KW - Tauola KW - Tool KW - WZ Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225421 VL - 78 IS - 293 ER - TY - JOUR T1 - Search for heavy resonances decaying into \({WW}\) in the eνμν final state in \({pp}\) collisions at root s=13 TeV with the ATLAS detector JF - European Physical Journal C N2 - A search for neutral heavy resonances is performed in the WW -> e nu mu nu decay channel using pp collision data corresponding to an integrated luminosity of 36.1 fb(-1), collected at a centre-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. No evidence of such heavy resonances is found. In the search for production via the quark-antiquark annihilation or gluon-gluon fusion process, upper limits on sigma(X) x B(X -> WW) as a function of the resonance mass are obtained in the mass range between 200 GeV and up to 5 TeV for various benchmark models: a Higgs-like scalar in different width scenarios, a two-Higgs-doublet model, a heavy vector triplet model, and a warped extra dimensions model. In the vector-boson fusion process, constraints are also obtained on these resonances, as well as on a Higgs boson in the Georgi-Machacek model and a heavy tensor particle coupling only to gauge bosons. KW - Gluon Fusion KW - Higgs KW - Bosons KW - Mass Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225914 VL - 78 IS - 24 ER - TY - JOUR T1 - Constraints on off-shell Higgs boson production and the Higgs boson total width in \(ZZ\) → 4l and \(ZZ\) → 2l2ν final states with the ATLAS detector JF - Physics Letters B N2 - A measurement of off-shell Higgs boson production in the ZZ -> 4l and ZZ -> 2l2v decay channels, where stands for either an electron or a muon, is performed using data from proton-proton collisions at a centre-of-mass energy of root s = 13 TeV. The data were collected by the ATLAS experiment in 2015 and 2016 at the Large Hadron Collider, and they correspond to an integrated luminosity of 36.1 fb(-1). An observed (expected) upper limit on the off-shell Higgs signal strength, defined as the event yield normalised to the Standard Model prediction, of 3.8 (3.4) is obtained at 95% confidence level (CL). Assuming the ratio of the Higgs boson couplings to the Standard Model predictions is independent of the momentum transfer of the Higgs production mechanism considered in the analysis, a combination with the on-shell signal-strength measurements yields an observed (expected) 95% CL upper limit on the Higgs boson total width of 14.4 (15.2) MeV. KW - Parton Distributions KW - Search KW - Decay KW - Mass Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-346791 VL - 786 ER - TY - JOUR A1 - Dreiner, Herbi K. A1 - Krauss, Manuel E. A1 - O'Leary, Ben A1 - Opferkuch, Toby A1 - Staub, Florian T1 - Validity of the CMSSM interpretation of the diphoton excess JF - Physical Review D N2 - It has been proposed that the observed diphoton excess at 750 GeV could be explained within the constrained minimal supersymmetric standard model via resonantly produced stop bound states. We reanalyze this scenario critically and extend previous work to include the constraints from the stability of the electroweak vacuum and from the decays of the stoponium into a pair of Higgs bosons. It is shown that the interesting regions of parameter space with a light stop and Higgs of the desired mass are ruled out by these constraints. This conclusion is not affected by the presence of the bound states because the binding energy is usually very small in the regions of parameter space which can explain the Higgs mass. Thus, this also leads to strong constraints on the diphoton production cross section which is in general too small. KW - Minimal supersymmetric model KW - 2-loop level KW - Bound-states KW - Higgs-boson KW - MSSM KW - Mass KW - Spheno KW - Sarah KW - Spectrum KW - Breaking Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-187429 VL - 94 IS - 5 ER -