Search for pair production of up-type vector-like quarks and for four-top-quark events in final states with multiple b-jets with the ATLAS detector

doi:10.1007/JHEP07(2018)089

	Search for pair production of up-type vector-like quarks and for four-top-quark events in final states with multiple b-jets with the ATLAS detector
	ATLAS Collaboration
刊名	JOURNAL OF HIGH ENERGY PHYSICS
	2018
期号	7 页码:89
关键词	Beyond Standard Model Hadron-Hadron scattering (experiments) vector-like quarks
ISSN号	1029-8479
DOI	10.1007/JHEP07(2018)089
文献子类	Article
英文摘要	A search for pair production of up-type vector-like quarks (T) with a significant branching ratio into a top quark and either a Standard Model Higgs boson or a Z boson is presented. The same analysis is also used to search for four-top-quark production in several new physics scenarios. The search is based on a dataset of pp collisions at root s = 13TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider and corresponds to an integrated luminosity of 36.1 fb(-1). Data are analysed in the lepton+jets final state, characterised by an isolated electron or muon with high transverse momentum, large missing transverse momentum and multiple jets, as well as the jets+E-T(miss) final state, characterised by multiple jets and large missing transverse momentum. The search exploits the high multiplicity of jets identified as originating from b-quarks, and the presence of boosted, hadronically decaying top quarks and Higgs bosons reconstructed as large-radius jets, characteristic of signal events. No significant excess above the Standard Model expectation is observed, and 95% CL upper limits are set on the production cross sections for the different signal processes considered. These cross-section limits are used to derive lower limits on the mass of a vector-like T quark under several branching ratio hypotheses assuming contributions from T -> Wb, Zt, Ht decays. The 95% CL observed lower limits on the T quark mass range between 0.99TeV and 1.43TeV for all possible values of the branching ratios into the three decay modes considered, significantly extending the reach beyond that of previous searches. Additionally, upper limits on anomalous four-top-quark production are set in the context of an effective field theory model, as well as in an universal extra dimensions model.
WOS关键词	HIGGS-BOSON ; PARTON DISTRIBUTIONS ; HADRON COLLIDERS ; STANDARD MODEL ; PLUS PLUS ; LHC ; COLLISIONS ; BREAKING ; PARTICLE ; PROGRAM
WOS研究方向	Physics
语种	英语
WOS记录号	WOS:000438622000007
内容类型	期刊论文
源URL	[http://ir.ihep.ac.cn/handle/311005/286130]
专题	高能物理研究所_实验物理中心
作者单位	中国科学院高能物理研究所
推荐引用方式 GB/T 7714	ATLAS Collaboration. Search for pair production of up-type vector-like quarks and for four-top-quark events in final states with multiple b-jets with the ATLAS detector[J]. JOURNAL OF HIGH ENERGY PHYSICS,2018(7):89.
APA	ATLAS Collaboration.(2018).Search for pair production of up-type vector-like quarks and for four-top-quark events in final states with multiple b-jets with the ATLAS detector.JOURNAL OF HIGH ENERGY PHYSICS(7),89.
MLA	ATLAS Collaboration."Search for pair production of up-type vector-like quarks and for four-top-quark events in final states with multiple b-jets with the ATLAS detector".JOURNAL OF HIGH ENERGY PHYSICS .7(2018):89.