@article{3a5ddb65fe8b4b4b89936826207ab11f,
title = "Measurement of the W boson polarisation in tt¯ events from pp collisions at √s = 8 TeV in the lepton + jets channel with ATLAS",
abstract = "This paper presents a measurement of the polarisation of W bosons from tt¯ decays, reconstructed in events with one high-pT lepton and at least four jets. Data from pp collisions at the LHC were collected at s = 8 TeV and correspond to an integrated luminosity of 20.2 fb- 1. The angle θ∗ 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 θ∗ 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 F0=0.709±0.019, FL=0.299±0.015 and FR=-0.008±0.014, and are the most precisely measured W boson polarisation fractions to date. Limits on anomalous couplings of the Wtb vertex are set.",
author = "{The ATLAS collaboration} and M. Aaboud and G. Aad and B. Abbott and J. Abdallah and O. Abdinov and B. Abeloos and AbouZeid, {O. S.} and Abraham, {N. L.} and H. Abramowicz and H. Abreu and R. Abreu and Y. Abulaiti and Acharya, {B. S.} and S. Adachi and L. Adamczyk and Adams, {D. L.} and J. Adelman and S. Adomeit and T. Adye and Affolder, {A. A.} and T. Agatonovic-Jovin and Aguilar-Saavedra, {J. A.} and Ahlen, {S. P.} and F. Ahmadov and G. Aielli and H. Akerstedt and {\AA}kesson, {T. P.A.} and Akimov, {A. V.} and Alberghi, {G. L.} and J. Albert and S. Albrand and {Alconada Verzini}, {M. J.} and M. Aleksa and Aleksandrov, {I. N.} and C. Alexa and G. Alexander and T. Alexopoulos and M. Alhroob and B. Ali and M. Aliev and G. Alimonti and J. Alison and Alkire, {S. P.} and Allbrooke, {B. M.M.} and Allen, {B. W.} and Allport, {P. P.} and A. Aloisio and A. Alonso and F. Alonso and C. Alpigiani and Alshehri, {A. A.} and M. Alstaty and {Alvarez Gonzalez}, B. and {{\'A}lvarez Piqueras}, D. and Alviggi, {M. G.} and Amadio, {B. T.} and {Amaral Coutinho}, Y. and C. Amelung and D. Amidei and {Amor Dos Santos}, {S. P.} and A. Amorim and S. Amoroso and G. Amundsen and C. Anastopoulos and Ancu, {L. S.} and N. Andari and T. Andeen and Anders, {C. F.} and Anders, {J. K.} and Anderson, {K. J.} and A. Andreazza and V. Andrei and S. Angelidakis and I. Angelozzi and A. Angerami and F. Anghinolfi and Anisenkov, {A. V.} and N. Anjos and A. Annovi and C. Antel and M. Antonelli and A. Antonov and Antrim, {D. J.} and F. Anulli and M. Aoki and {Aperio Bella}, L. and G. Arabidze and Y. Arai and Araque, {J. P.} and {Araujo Ferraz}, V. and Arce, {A. T.H.} and Arduh, {F. A.} and Arguin, {J. F.} and S. Argyropoulos and M. Arik and Armbruster, {A. J.} and Armitage, {L. J.} and O. Arnaez and H. Arnold and M. Arratia and O. Arslan and A. Artamonov and G. Artoni and S. Artz and S. Asai and N. Asbah and A. Ashkenazi and B. {\AA}sman and L. Asquith and K. Assamagan and R. Astalos and M. Atkinson and Atlay, {N. B.} and K. Augsten and G. Avolio and B. Axen and Ayoub, {M. K.} and G. Azuelos and Baak, {M. A.} and Baas, {A. E.} and Baca, {M. J.} and H. Bachacou and K. Bachas and M. Backes and M. Backhaus and P. Bagiacchi and P. Bagnaia and Y. Bai and Baines, {J. T.} and M. Bajic and Baker, {O. K.} and Baldin, {E. M.} and P. Balek and T. Balestri and F. Balli and Balunas, {W. K.} and E. Banas and Sw Banerjee and Bannoura, {A. A.E.} and L. Barak and Barberio, {E. L.} and D. Barberis and M. Barbero and T. Barillari and Barisits, {M. S.} and T. Barklow and N. Barlow and Barnes, {S. L.} and Barnett, {B. M.} and Barnett, {R. M.} and Z. Barnovska-Blenessy and A. Baroncelli and G. Barone and Barr, {A. J.} and {Barranco Navarro}, L. and F. Barreiro and {Barreiro Guimar{\~a}es da Costa}, J. and R. Bartoldus and Barton, {A. E.} and P. Bartos and A. Basalaev and A. Bassalat and Bates, {R. L.} and Batista, {S. J.} and Batley, {J. R.} and M. Battaglia and M. Bauce and F. Bauer and Bawa, {H. S.} and Beacham, {J. B.} and Beattie, {M. D.} and T. Beau and Beauchemin, {P. H.} and P. Bechtle and Beck, {H. P.} and K. Becker and M. Becker and M. Beckingham and C. Becot and Beddall, {A. J.} and A. Beddall and Bednyakov, {V. A.} and M. Bedognetti and Bee, {C. P.} and Beemster, {L. J.} and Beermann, {T. A.} and M. Begel and Behr, {J. K.} and Bell, {A. S.} and G. Bella and L. Bellagamba and A. Bellerive and M. Bellomo and K. Belotskiy and O. Beltramello and Belyaev, {N. L.} and O. Benary and D. Benchekroun and M. Bender and X. Zhao",
note = "Publisher Copyright: {\textcopyright} 2017, CERN for the benefit of the ATLAS collaboration.",
year = "2017",
month = apr,
day = "1",
doi = "10.1140/epjc/s10052-017-4819-4",
language = "English",
volume = "77",
journal = "European Physical Journal C",
issn = "1434-6044",
number = "4",
}