TY  - JOUR
AU  - ATLAS Collaboration (Aaboud, M. et al
AU  - Alvarez Piqueras, D.
AU  - Barranco Navarro, L.
AU  - Cabrera Urban, S.
AU  - Castillo Gimenez, V.
AU  - Cerda Alberich, L.
AU  - Costa, M. J.
AU  - Fernandez Martinez, P.
AU  - Ferrer, A.
AU  - Fiorini, L.
AU  - Fuster, J.
AU  - Garcia, C.
AU  - Garcia Navarro, J. E.
AU  - Gonzalez de la Hoz, S.
AU  - Higon-Rodriguez, E.
AU  - Jimenez Pena, J.
AU  - King, M.
AU  - Lacasta, C.
AU  - Mamuzic, J.
AU  - Marti-Garcia, S.
AU  - Melini, D.
AU  - Mitsou, V. A.
AU  - Pedraza Lopez, S.
AU  - Rodriguez Rodriguez, D.
AU  - Romero Adam, E.
AU  - Ros, E.
AU  - Salt, J.
AU  - Sanchez Martinez, V.
AU  - Soldevila, U.
AU  - Sanchez, J.
AU  - Valero, A.
AU  - Valls Ferrer, J. A.
AU  - Vos, M.
PY  - 2017
DA  - 2017//
TI  - Measurement of the W boson polarisation in t(t)over-barevents from pp collisions at root s=8 TeV in the lepton plus jets channel with ATLAS
T2  - Eur. Phys. J. C
JO  - European Physical Journal C
SP  - 264
EP  - 28pp
VL  - 77
IS  - 4
PB  - Springer
AB  - This paper presents a measurement of the polarisation of W bosons from t (t) over bar t decays, reconstructed in events with one high-p(T) lepton and at least four jets. Data from pp collisions at the LHC were collected at root s = 8 TeV and correspond to an integrated luminosity of 20.2 fb(-1). The angle theta* 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 theta* 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-0 = 0.709 +/- 0.019, F-L = 0.299 +/- 0.015 and F-R = – 0.008 +/- 0.014, and are the most precisely measured W boson polarisation fractions to date. Limits on anomalous couplings of the W tb vertex are set.
SN  - 1434-6044
UR  - http://arxiv.org/abs/1612.02577
UR  - https://doi.org/10.1140/epjc/s10052-017-4819-4
DO  - 10.1140/epjc/s10052-017-4819-4
LA  - English
N1  - WOS:000400235900001
ID  - ATLASCollaborationAaboud_etal2017
ER  -