标题：Measurements of top quark spin observables in tt¯ events using dilepton final states in √s=8 TeV pp collisions with the ATLAS detector
作者：The ATLAS collaboration; Aaboud M.; Aad G.; Abbott B.; Abdallah J.; Abdinov O.; Abeloos B.; AbouZeid O.S.;等 更多 作者机构：[ Aaboud, M] Faculté des Sciences, Université Mohamed Premier and LPTPM, Oujda, Morocco;[ Aad, G] CPPM, Aix-Marseille Université and CNRS/IN2P3, Marse 更多
通讯作者地址：[Jackson, P] Department of Physics, University of AdelaideAustralia
来源：Journal of High Energy Physics
关键词：Hadron-Hadron scattering (experiments)
摘要：Measurements of top quark spin observables in tt¯ events are presented based on 20.2 fb−1 of s=8 TeV proton-proton collisions recorded with the ATLAS detector at the LHC. The analysis is performed in the dilepton final state, characterised by the presence of two isolated leptons (electrons or muons). There are 15 observables, each sensitive to a different coefficient of the spin density matrix of tt¯ production, which are measured independently. Ten of these observables are measured for the first time. All of them are corrected for detector resolution and acceptance effects back to the parton and stable-particle levels. The measured values of the observables at parton level are compared to Standard Model predictions at next-to-leading order in QCD. The corrected distributions at stable-particle level are presented and the means of the distributions are compared to Monte Carlo predictions. No significant deviation from the Standard Model is observed for any observable.[Figure not available: see fulltext.] © 2017, The Author(s).