@article{OPUS4-13156, title = {Search for WH production with a light Higgs boson decaying to prompt electron-jets in proton-proton collisions at \(\sqrt {s}=7\)  TeV with the ATLAS detector}, series = {New Journal of Physics}, volume = {15}, journal = {New Journal of Physics}, number = {043009}, organization = {The ATLAS Collaboration}, doi = {10.1088/1367-2630/15/4/043009}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-131565}, year = {2013}, abstract = {A search is performed for WH production with a light Higgs boson decaying to hidden-sector particles resulting in clusters of collimated electrons, known as electron-jets. The search is performed with \(2.04 fb^{-1}\) of data collected in 2011 with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at \(\sqrt {s}=7 TeV\) . One event satisfying the signal selection criteria is observed, which is consistent with the expected background rate. Limits on the product of the WH production cross section and the branching ratio of a Higgs boson decaying to prompt electron-jets are calculated as a function of a Higgs boson mass in the range from 100 to 140 GeV.}, language = {en} } @article{OPUS4-15019, title = {Search for the Standard Model Higgs boson produced in association with top quarks and decaying into b\(\overline{b}\) in pp collisions at \(\sqrt {s}\) = 8 TeV with the ATLAS detector}, series = {European Physical Journal C: Particles and Fields}, volume = {75}, journal = {European Physical Journal C: Particles and Fields}, number = {7}, organization = {ATLAS Collaboration}, doi = {10.1140/epjc/s10052-015-3543-1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-150197}, pages = {349}, year = {2015}, abstract = {A search for the Standard Model Higgs boson produced in association with a top-quark pair, t\(\overline{t}\)H, is presented. The analysis uses 20.3 fb\(^{-1}\) of pp collision data at \(\sqrt {s}\) = 8 TeV, collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the H→b\(\overline{b}\) decay mode and uses events containing one or two electrons or muons. In order to improve the sensitivity of the search, events are categorised according to their jet and b-tagged jet multiplicities. A neural network is used to discriminate between signal and background events, the latter being dominated by t\(\overline{t}\)+jets production. In the single-lepton channel, variables calculated using a matrix element method are included as inputs to the neural network to improve discrimination of the irreducible t\(\overline{t}\)+b\(\overline{b}\) background. No significant excess of events above the background expectation is found and an observed (expected) limit of 3.4 (2.2) times the Standard Model cross section is obtained at 95 \% confidence level. The ratio of the measured t\(\overline{t}\)H signal cross section to the Standard Model expectation is found to be μ = 1.5 ± 1.1 assuming a Higgs boson mass of 125 GeV.}, language = {en} } @article{OPUS4-14423, title = {Search for the associated production of the Higgs boson with a top quark pair in multilepton final states with the ATLAS detector}, series = {Physics Letters B}, volume = {749}, journal = {Physics Letters B}, organization = {ATLAS Collaboration}, doi = {10.1016/j.physletb.2015.07.079}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-144231}, pages = {519-541}, year = {2015}, abstract = {A search for the associated production of the Higgs boson with a top quark pair is performed in multilepton final states using 20.3 fb\(^{-1}\) of proton-proton collision data recorded by the ATLAS experiment at \(\sqrt {s}\)=8 TeV at the Large Hadron Collider. Five final states, targeting the decays H→WW\(^{*}\), ττ, and ZZ\(^{*}\), are examined for the presence of the Standard Model (SM) Higgs boson: two same-charge light leptons (e or μ) without a hadronically decaying τ lepton; three light leptons; two same-charge light leptons with a hadronically decaying τ lepton; four light leptons; and one light lepton and two hadronically decaying τ leptons. No significant excess of events is observed above the background expectation. The best fit for the t\(\overline{t}\)H production cross section, assuming a Higgs boson mass of 125 GeV, is 2.1\(^{+1.4}_{-1.2}\) times the SM expectation, and the observed (expected) upper limit at the 95\% confidence level is 4.7 (2.4) times the SM rate. The p-value for compatibility with the background-only hypothesis is 1.8σ; the expectation in the presence of a Standard Model signal is 0.9σ.}, language = {en} } @article{OPUS4-15012, title = {Search for invisible decays of the Higgs boson produced in association with a hadronically decaying vector boson in pp collisions at \(\sqrt {s}\) = TeV with the ATLAS detector}, series = {European Physical Journal C: Particles and Fields}, volume = {75}, journal = {European Physical Journal C: Particles and Fields}, number = {7}, organization = {ATLAS Collaboration}, doi = {10.1140/epjc/s10052-015-3551-1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-150126}, pages = {337}, year = {2015}, abstract = {A search for Higgs boson decays to invisible particles is performed using 20.3 fb\(^{-1}\) of pp collision data at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector at the Large Hadron Collider. The process considered is Higgs boson production in association with a vector boson (V = W or Z) that decays hadronically, resulting in events with two or more jets and large missing transverse momentum. No excess of candidates is observed in the data over the background expectation. The results are used to constrain VH production followed by H decaying to invisible particles for the Higgs boson mass range 115 < m\(_{H}\) < 300 GeV. The 95 \% confidence-level observed upper limit on σ\(_{VH}\) × BR(H → inv.) varies from 1.6 pb at 115 GeV to 0.13 pb at 300 GeV. Assuming Standard Model production and including the gg → H contribution as signal, the results also lead to an observed upper limit of 78 \% at 95 \% confidence level on the branching ratio of Higgs bosons decays to invisible particles at a mass of 125 GeV.}, language = {en} } @article{OPUS4-13610, title = {Search for H→γγH→γγ produced in association with top quarks and constraints on the Yukawa coupling between the top quark and the Higgs boson using data taken at 7 TeV and 8 TeV with the ATLAS detector}, series = {Physics Letters B}, volume = {740}, journal = {Physics Letters B}, organization = {ATLAS Collaboration}, doi = {10.1016/j.physletb.2014.11.049}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-136100}, pages = {222-242}, year = {2015}, abstract = {A search is performed for Higgs bosons produced in association with top quarks using the diphoton decay mode of the Higgs boson. Selection requirements are optimized separately for leptonic and fully hadronic final states from the top quark decays. The dataset used corresponds to an integrated luminosity of 4.5 fb\(^{-1}\) of proton-proton collisions at a center-of-mass energy of 7 TeV and 20.3 fb-120.3 fb\(^{-1}\) at 8 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. No significant excess over the background prediction is observed and upper limits are set on the \(t\overline{t}H\) production cross section. The observed exclusion upper limit at 95\% confidence level is 6.7 times the predicted Standard Model cross section value. In addition, limits are set on the strength of the Yukawa coupling between the top quark and the Higgs boson, taking into account the dependence of the \(t\overline{t}H\) and tH   cross sections as well as the H→γγH→γγ branching fraction on the Yukawa coupling. Lower and upper limits at 95\% confidence level are set at -1.3 and +8.0 times the Yukawa coupling strength in the Standard Model.}, language = {en} } @article{OPUS4-15011, title = {Search for Higgs boson pair production in the b\(\overline{b}\)b\(\overline{b}\) final state from pp collisions at \(\sqrt {s}\) = 8 TeV with the ATLAS detector}, series = {European Physical Journal C: Particles and Fields}, volume = {75}, journal = {European Physical Journal C: Particles and Fields}, number = {9}, organization = {ATLAS Collaboration}, doi = {10.1140/epjc/s10052-015-3628-x}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-150119}, pages = {412}, year = {2015}, abstract = {A search for Higgs boson pair production pp → hh is performed with 19.5 fb\(^{-1}\) of proton-proton collision data at \(\sqrt {s}\) = 8 TeV, which were recorded by the ATLAS detector at the Large Hadron Collider in 2012. The decay products of each Higgs boson are reconstructed as a high-momentum b\(\overline{b}\) system with either a pair of small-radius jets or a single large-radius jet, the latter exploiting jet substructure techniques and associated b-tagged track-jets. No evidence for resonant or non-resonant Higgs boson pair production is observed. The data are interpreted in the context of the Randall-Sundrum model with a warped extra dimension as well as the two-Higgs-doublet model. An upper limit on the cross-section for pp → G\(^{*}_{KK}\) → hh → b\(\overline{b}\)b\(\overline{b}\) of 3.2(2.3) fb is set for a Kaluza-Klein graviton G\(^{*}_{KK}\) mass of 1.0(1.5) TeV, at the 95 \% confidence level. The search for non-resonant Standard Model hh production sets an observed 95 \% confidence level upper limit on the production cross-section σ(pp → hh → b\(\overline{b}\)b\(\overline{b}\)) of 202 fb, compared to a Standard Model prediction of σ(pp → hh → b\(\overline{b}\)b\(\overline{b}\)) = 3.6±0.5 fb.}, 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{OPUS4-15009, title = {Search for direct pair production of a chargino and a neutralino decaying to the 125 GeV Higgs boson in \(\sqrt {s}\) = 8 TeV pp collisions with the ATLAS detector}, series = {European Physical Journal C: Particles and Fields}, volume = {75}, journal = {European Physical Journal C: Particles and Fields}, number = {5}, organization = {ATLAS Collaboration}, doi = {10.1140/epjc/s10052-015-3408-7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-150099}, pages = {208}, year = {2015}, abstract = {A search is presented for the direct pair production of a chargino and a neutralino pp → \(\tilde{χ}\)\(^{±}_{1}\)\(\tilde{χ}\)\(^{0}_{2}\), where the chargino decays to the lightest neutralino and the W boson, \(\tilde{χ}\)\(^{±}_{1}\)→\(\tilde{χ}\)\(^{0}_{1}\)(W\(^{±}\)→ℓ\(^{±}\)ν), while the neutralino decays to the lightest neutralino and the 125 GeV Higgs boson, \(\tilde{χ}\)\(^{0}_{2}\)→\(\tilde{χ}\)\(^{0}_{1}\)(h→bb/γγ/ℓ\(^{±}\)νqq). The final states considered for the search have large missing transverse momentum, an isolated electron or muon, and one of the following: either two jets identified as originating from bottom quarks, or two photons, or a second electron or muon with the same electric charge. The analysis is based on 20.3 fb\(^{-1}\) of \(\sqrt {s}\) = 8 TeV proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with the Standard Model expectations, and limits are set in the context of a simplified supersymmetric model.}, language = {en} } @article{OPUS4-15007, title = {Search for a new resonance decaying to a W or Z boson and a Higgs boson in the ℓℓ/ℓν/νν+b\(\overline{b}\) final states with the ATLAS detector}, series = {European Physical Journal C: Particles and Fields}, volume = {75}, journal = {European Physical Journal C: Particles and Fields}, number = {6}, organization = {ATLAS Collaboration}, doi = {10.1140/epjc/s10052-015-3474-x}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-150075}, pages = {263}, year = {2015}, abstract = {A search for a new resonance decaying to a W or Z boson and a Higgs boson in the ℓℓ/ℓν/νν+b\(\overline{b}\) final states is performed using 20.3 fb\(^{-1}\) of pp collision data recorded at \(\sqrt {s}\) = 8 TeV with the ATLAS detector at the Large Hadron Collider. The search is conducted by examining the WH / ZH invariant mass distribution for a localized excess. No significant deviation from the Standard Model background prediction is observed. The results are interpreted in terms of constraints on the Minimal Walking Technicolor model and on a simplified approach based on a phenomenological Lagrangian of Heavy Vector Triplets.}, language = {en} } @article{DennerLangUccirati2017, author = {Denner, Ansgar and Lang, Jean-Nicolas and Uccirati, Sandro}, title = {NLO electroweak corrections in extended Higgs sectors with RECOLA2}, series = {Journal of High Energy Physics}, volume = {7}, journal = {Journal of High Energy Physics}, number = {87}, doi = {10.1007/JHEP07(2017)087}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170673}, year = {2017}, abstract = {We present the computer code RECOLA2 along with the first NLO electroweak corrections to Higgs production in vector-boson fusion and updated results for Higgs strahlung in the Two-Higgs-Doublet Model and Higgs-Singlet extension of the Standard Model. A fully automated procedure for the generation of tree-level and one-loop matrix elements in general models, including renormalization, is presented. We discuss the application of the Background-Field Method to the extended models. Numerical results for NLO electroweak cross sections are presented for different renormalization schemes in the Two-Higgs-Doublet Model and the Higgs-Singlet extension of the Standard Model. Finally, we present distributions for the production of a heavy Higgs boson.}, language = {en} }