TY  - JOUR
T1  - Identification of boosted Higgs bosons decaying into \(b\)-quark pairs with the ATLAS detector at 13 TeV
JF  - European Physical Journal C
N2  - This paper describes a study of techniques for identifying Higgs bosons at high transverse momenta decaying into bottom-quark pairs, H -> b (b) over bar, for proton-proton collision data collected by the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy root s = 13 TeV. These decays are reconstructed from calorimeter jets found with the anti-k(t) R = 1.0 jet algorithm. To tag Higgs bosons, a combination of requirements is used: b-tagging of R = 0.2 track-jets matched to the large-R calorimeter jet, and requirements on the jet mass and other jet substructure variables. The Higgs boson tagging efficiency and corresponding multijet and hadronic top-quark background rejections are evaluated using Monte Carlo simulation. Several benchmark tagging selections are defined for different signal efficiency targets. The modelling of the relevant input distributions used to tag Higgs bosons is studied in 36 fb(-1) of data collected in 2015 and 2016 using g -> b (b) over bar and Z(-> b (b) over bar)gamma event selections in data. Both processes are found to be well modelled within the statistical and systematic uncertainties.
KW  - Parton distributions
KW  - PP collisions
KW  - search
KW  - MASS
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-226812
VL  - 79
IS  - 836
ER  - 
TY  - JOUR
T1  - Evidence for the associated production of the Higgs boson and a top quark pair with the ATLAS detector
JF  - Physical Review D
N2  - 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.
KW  - Production cross-section
KW  - spontaneous symmetry breaking
KW  - Higgs bosons
KW  - Top quark
KW  - Parton distributions
KW  - pp collisions
KW  - Monte-Carlo
KW  - 8 TEV
KW  - Root  s=7
KW  - search
KW  - decay
KW  - model
KW  - symmetries
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-226569
VL  - 97
ER  -