Search for pair production of Higgs bosons in the bb¯bb¯ final state using proton-proton collisions at sqrt(s)=13 TeV with the ATLAS detector
Physical Review D American Physical Society 94:5 (2016) 1-29
Abstract:
A search for Higgs-boson pair production in the bb¯bb¯ final state is carried out with 3.2 fb−1 of proton-proton collision data collected at s√=13 TeV with the ATLAS detector. The data are consistent with the estimated background and are used to set upper limits on the production cross section of Higgs-boson pairs times branching ratio to bb¯bb¯ for both nonresonant and resonant production. In the case of resonant production of Kaluza-Klein gravitons within the Randall-Sundrum model, upper limits in the 24 to 91 fb range are obtained for masses between 600 and 3000 GeV, at the 95% confidence level. The production cross section times branching ratio for nonresonant Higgs-boson pairs is also constrained to be less than 1.22 pb, at the 95% confidence level.Search for TeV-scale gravity signatures in high-mass final states with leptons and jets with the ATLAS detector at √s=13 TeV
Physics Letters B Elsevier 760 (2016) 520-537
Abstract:
A search for physics beyond the Standard Model, in final states with at least one high transverse momentum charged lepton (electron or muon) and two additional high transverse momentum leptons or jets, is performed using 3.2 fb−1 of proton–proton collision data recorded by the ATLAS detector at the Large Hadron Collider in 2015 at √s=13 TeV source. The upper end of the distribution of the scalar sum of the transverse momenta of leptons and jets is sensitive to the production of high-mass objects. No excess of events beyond Standard Model predictions is observed. Exclusion limits are set for models of microscopic black holes with two to six extra dimensions.Boosting Higgs pair production in the bbbb final state with multivariate techniques
European Physical Journal C Springer Verlag 76:386 (2016)
Abstract:
The measurement of Higgs pair production will be a cornerstone of the LHC program in the coming years. Double Higgs production provides a crucial window upon the mechanism of electroweak symmetry breaking and has a unique sensitivity to the Higgs trilinear coupling. We study the feasibility of a measurement of Higgs pair production in the b ¯bb¯b final state at the LHC. Our analysis is based on a combination of traditional cut-based methods with state-of-the-art multivariate techniques. We account for all relevant backgrounds, including the contributions from light and charm jet mis-identification, which are ultimately comparable in size to the irreducible 4b QCD background. We demonstrate the robustness of our analysis strategy in a high pileup environment. For an integrated luminosity of L = 3 ab−1 , a signal significance of S/√ B ' 3 is obtained, indicating that the b ¯bb¯b final state alone could allow for the observation of double Higgs production at the High Luminosity LHC.Identification of high transverse momentum top quarks in pp collisions at √s = 8 TeV with the ATLAS detector
Journal of High Energy Physics Springer 2016:6 (2016)
Abstract:
This paper presents studies of the performance of several jet-substructure techniques, which are used to identify hadronically decaying top quarks with high transverse momentum contained in large-radius jets. The efficiency of identifying top quarks is measured using a sample of top-quark pairs and the rate of wrongly identifying jets from other quarks or gluons as top quarks is measured using multijet events collected with the ATLAS experiment in 20.3 fb^−1 of 8 TeV proton-proton collisions at the Large Hadron Collider. Predictions from Monte Carlo simulations are found to provide an accurate description of the performance. The techniques are compared in terms of signal efficiency and background rejection using simulations, covering a larger range in jet transverse momenta than accessible in the dataset. Additionally, a novel technique is developed that is optimized to reconstruct top quarks in events with many jets.A new method to distinguish hadronically decaying boosted Z bosons from W bosons using the ATLAS detector
European Physical Journal C Springer Verlag 76:5 (2016)