TY  - SER
AU  - Aaboud,M.
AU  - Abbott,B.
AU  - Chelkov,G.A.
AU  - Aad,G.
AU  - Vaniachine,A.
TI  - Measurement of the W boson polarisation in tt¯ events from pp collisions at √s = 8 TeV in the lepton + jets channel with ATLAS
KW  - ATLAS, детектор
KW  - Большой адронный коллайдер
KW  - протон-протонные столкновения
KW  - W-бозон
KW  - лептоны
KW  - статьи в журналах
N1  - Библиогр.: 82 назв
N2  - This paper presents a measurement of the polarisation of W bosons from tar{t} decays, reconstructed in events with one high-p_{ ext{ T }} lepton and at least four jets. Data from pp collisions at the LHC were collected at sqrt{s} = 8 TeV and correspond to an integrated luminosity of 20.2 fb^{-1}. The angle  heta ^{*} between the b-quark from the top quark decay and a direct W boson decay product in the W boson rest frame is sensitive to the W boson polarisation. Two different W decay products are used as polarisation analysers: the charged lepton and the down-type quark for the leptonically and hadronically decaying W boson, respectively. The most precise measurement of the W boson polarisation via the distribution of cos { heta ^{*}} is obtained using the leptonic analyser and events in which at least two of the jets are tagged as b-quark jets. The fitted fractions of longitudinal, left- and right-handed polarisation states are F_{mathrm {0}}=~0.709~pm ~{0.019}, F_{mathrm {L}}=~0.299~pm ~{0.015} and F_{mathrm {R}}=~-0.008~pm ~{0.014}, and are the most precisely measured W boson polarisation fractions to date. Limits on anomalous couplings of the Wtb vertex are set
UR  - http://vital.lib.tsu.ru/vital/access/manager/Repository/vtls:000582060
ER  -