Search for top-quark decays t -> Hq with 36 fb(-1) of pp collision data at root s=13 TeV with the ATLAS detectorShow others and affiliations
Number of Authors: 29342019 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 5, article id 123
Article in journal (Refereed) Published
Abstract [en]
A search for flavour-changing neutral current decays of a top quark into an up-type quark (q = u, c) and the Standard Model Higgs boson, t Hq, is presented. The search is based on a dataset of pp collisions at = 13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 36.1 fb(-1). Two complementary analyses are performed to search for top-quark pair events in which one top quark decays into Wb and the other top quark decays into Hq, and target the Hbb and H (+-) decay modes, respectively. The high multiplicity of b-quark jets, or the presence of hadronically decaying -leptons, is exploited in the two analyses respectively. Multivariate techniques are used to separate the signal from the background, which is dominated by top-quark pair production. No significant excess of events above the background expectation is found, and 95% CL upper limits on the t Hq branching ratios are derived. The combination of these searches with ATLAS searches in diphoton and multilepton final states yields observed (expected) 95% CL upper limits on the t Hc and t Hu branching ratios of 1.1 x 10(-3) (8.3 x 10(-4)) and 1.2 x 10(-3) (8.3 x 10(-4)), respectively. The corresponding combined observed (expected) upper limits on the |(tcH)| and |(tuH)| couplings are 0.064 (0.055) and 0.066 (0.055), respectively.
Place, publisher, year, edition, pages
SPRINGER , 2019. no 5, article id 123
Keywords [en]
Hadron-Hadron scattering (experiments), Rare decay, Top physics, NNER A, 1991, NUCLEAR PHYSICS B, V358, P46 boud M. yy, 2017, EUROPEAN PHYSICAL JOURNAL C, V77, d G., 2017, EUROPEAN PHYSICAL JOURNAL C, V77, son P, 2004, JOURNAL OF HIGH ENERGY PHYSICS, d G., 2016, EUROPEAN PHYSICAL JOURNAL C, V76, boud M., 2016, EUROPEAN PHYSICAL JOURNAL C, V76, boud M., 2016, PHYSICS LETTERS B, V762, P1 d G., 2016, JOURNAL OF HIGH ENERGY PHYSICS, uilar-Saavedra JA, 2004, ACTA PHYSICA POLONICA BMeeting on Particle Physics Phenomenology at High Energy Colliders, SEP 26-27, 2004, Montpellier, FRANCE, V35, P2695
National Category
Subatomic Physics
Identifiers
URN: urn:nbn:se:kth:diva-253736DOI: 10.1007/JHEP05(2019)123ISI: 000468948900001Scopus ID: 2-s2.0-85066135451OAI: oai:DiVA.org:kth-253736DiVA, id: diva2:1325774
Note
QC 20190617
2019-06-172019-06-172019-06-17Bibliographically approved