Analysis of the Wtb vertex from the measurement of triple-differential angular decay rates of single top quarks produced in the t-channel at √s=8 TeV with the ATLAS detector

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Analysis of the Wtb vertex from the measurement of triple-differential angular decay rates of single top quarks produced in the t-channel at √s=8 TeV with the ATLAS detector. / The ATLAS collaboration.

в: Journal of High Energy Physics, Том 2017, № 12, 17, 01.12.2017.

Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование

BibTeX

@article{a25895ef3e084b2a960fb940e033b625,

title = "Analysis of the Wtb vertex from the measurement of triple-differential angular decay rates of single top quarks produced in the t-channel at √s=8 TeV with the ATLAS detector",

abstract = "The electroweak production and subsequent decay of single top quarks in the t-channel is determined by the properties of the Wtb vertex, which can be described by the complex parameters of an effective Lagrangian. An analysis of a triple-differential decay rate in t-channel production is used to simultaneously determine five generalised helicity fractions and phases, as well as the polarisation of the produced top quark. The complex parameters are then constrained. This analysis is based on 20.2 fb−1 of proton-proton collision data at a centre-of-mass energy of 8 TeV collected with the ATLAS detector at the LHC. The fraction of decays containing transversely polarised W bosons is measured to be f1 = 0.30 ± 0.05. The phase between amplitudes for transversely and longitudinally polarised W bosons recoiling against left-handed b-quarks is measured to be δ− = 0.002π+ 0.017π + 0.016π, giving no indication of CP violation. The fractions of longitudinal or transverse W bosons accompanied by right-handed b-quarks are also constrained. Based on these measurements, limits are placed at 95% CL on the ratio of the complex coupling parameters Re [gR/VL ∈ [−0.12, 0.17] and Im [gR/VL ∈ [−0.07, 0.06]. Constraints are also placed on the ratios |VR/VL| and |gL/VL|. In addition, the polarisation of single top quarks in the t-channel is constrained to be P > 0.72 (95% CL). None of the above measurements make assumptions about the value of any of the other parameters or couplings and all of them are in agreement with the Standard Model.",

keywords = "Electroweak interaction, Hadron-Hadron scattering (experiments), Top physics, MONTE-CARLO, PARTON DISTRIBUTIONS, QCD, HADRON COLLIDERS, LHC, PAIR PRODUCTION, POLARIZATION",

author = "{The ATLAS collaboration} and M. Aaboud and G. Aad and B. Abbott and J. Abdallah and O. Abdinov and B. Abeloos and Abidi, {S. H.} 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 J. Adelman and M. Adersberger and T. Adye and Affolder, {A. A.} and T. Agatonovic-Jovin and C. Agheorghiesei and Aguilar-Saavedra, {J. A.} and Ahlen, {S. P.} and F. Ahmadov and G. Aielli and S. Akatsuka and H. Akerstedt and {\AA}kesson, {T. P.A.} and E. Akilli and Akimov, {A. V.} and Alberghi, {G. L.} and J. Albert and P. Albicocco and {Alconada Verzini}, {M. J.} and M. Aleksa and Aleksandrov, {I. N.} and C. Alexa and G. Alexander and Anisenkov, {A. V.} and Baldin, {E. M.} and Bobrovnikov, {V. S.} and Buzykaev, {A. R.} and Kazanin, {V. F.} and T. Kharlamova and Korol, {A. A.} and Peleganchuk, {S. V.} and Soukharev, {A. M.} and Talyshev, {A. A.} and Tikhonov, {Yu A.}",

note = "Publisher Copyright: {\textcopyright} 2017, The Author(s).",

year = "2017",

month = dec,

day = "1",

doi = "10.1007/JHEP12(2017)017",

language = "English",

volume = "2017",

journal = "Journal of High Energy Physics",

issn = "1029-8479",

publisher = "Springer US",

number = "12",

}

RIS

TY - JOUR

T1 - Analysis of the Wtb vertex from the measurement of triple-differential angular decay rates of single top quarks produced in the t-channel at √s=8 TeV with the ATLAS detector

AU - The ATLAS collaboration

AU - Aaboud, M.

AU - Aad, G.

AU - Abbott, B.

AU - Abdallah, J.

AU - Abdinov, O.

AU - Abeloos, B.

AU - Abidi, S. H.

AU - AbouZeid, O. S.

AU - Abraham, N. L.

AU - Abramowicz, H.

AU - Abreu, H.

AU - Abreu, R.

AU - Abulaiti, Y.

AU - Acharya, B. S.

AU - Adachi, S.

AU - Adamczyk, L.

AU - Adelman, J.

AU - Adersberger, M.

AU - Adye, T.

AU - Affolder, A. A.

AU - Agatonovic-Jovin, T.

AU - Agheorghiesei, C.

AU - Aguilar-Saavedra, J. A.

AU - Ahlen, S. P.

AU - Ahmadov, F.

AU - Aielli, G.

AU - Akatsuka, S.

AU - Akerstedt, H.

AU - Åkesson, T. P.A.

AU - Akilli, E.

AU - Akimov, A. V.

AU - Alberghi, G. L.

AU - Albert, J.

AU - Albicocco, P.

AU - Alconada Verzini, M. J.

AU - Aleksa, M.

AU - Aleksandrov, I. N.

AU - Alexa, C.

AU - Alexander, G.

AU - Anisenkov, A. V.

AU - Baldin, E. M.

AU - Bobrovnikov, V. S.

AU - Buzykaev, A. R.

AU - Kazanin, V. F.

AU - Kharlamova, T.

AU - Korol, A. A.

AU - Peleganchuk, S. V.

AU - Soukharev, A. M.

AU - Talyshev, A. A.

AU - Tikhonov, Yu A.

PY - 2017/12/1

Y1 - 2017/12/1

N2 - The electroweak production and subsequent decay of single top quarks in the t-channel is determined by the properties of the Wtb vertex, which can be described by the complex parameters of an effective Lagrangian. An analysis of a triple-differential decay rate in t-channel production is used to simultaneously determine five generalised helicity fractions and phases, as well as the polarisation of the produced top quark. The complex parameters are then constrained. This analysis is based on 20.2 fb−1 of proton-proton collision data at a centre-of-mass energy of 8 TeV collected with the ATLAS detector at the LHC. The fraction of decays containing transversely polarised W bosons is measured to be f1 = 0.30 ± 0.05. The phase between amplitudes for transversely and longitudinally polarised W bosons recoiling against left-handed b-quarks is measured to be δ− = 0.002π+ 0.017π + 0.016π, giving no indication of CP violation. The fractions of longitudinal or transverse W bosons accompanied by right-handed b-quarks are also constrained. Based on these measurements, limits are placed at 95% CL on the ratio of the complex coupling parameters Re [gR/VL ∈ [−0.12, 0.17] and Im [gR/VL ∈ [−0.07, 0.06]. Constraints are also placed on the ratios |VR/VL| and |gL/VL|. In addition, the polarisation of single top quarks in the t-channel is constrained to be P > 0.72 (95% CL). None of the above measurements make assumptions about the value of any of the other parameters or couplings and all of them are in agreement with the Standard Model.

AB - The electroweak production and subsequent decay of single top quarks in the t-channel is determined by the properties of the Wtb vertex, which can be described by the complex parameters of an effective Lagrangian. An analysis of a triple-differential decay rate in t-channel production is used to simultaneously determine five generalised helicity fractions and phases, as well as the polarisation of the produced top quark. The complex parameters are then constrained. This analysis is based on 20.2 fb−1 of proton-proton collision data at a centre-of-mass energy of 8 TeV collected with the ATLAS detector at the LHC. The fraction of decays containing transversely polarised W bosons is measured to be f1 = 0.30 ± 0.05. The phase between amplitudes for transversely and longitudinally polarised W bosons recoiling against left-handed b-quarks is measured to be δ− = 0.002π+ 0.017π + 0.016π, giving no indication of CP violation. The fractions of longitudinal or transverse W bosons accompanied by right-handed b-quarks are also constrained. Based on these measurements, limits are placed at 95% CL on the ratio of the complex coupling parameters Re [gR/VL ∈ [−0.12, 0.17] and Im [gR/VL ∈ [−0.07, 0.06]. Constraints are also placed on the ratios |VR/VL| and |gL/VL|. In addition, the polarisation of single top quarks in the t-channel is constrained to be P > 0.72 (95% CL). None of the above measurements make assumptions about the value of any of the other parameters or couplings and all of them are in agreement with the Standard Model.

KW - Electroweak interaction

KW - Hadron-Hadron scattering (experiments)

KW - Top physics

KW - MONTE-CARLO

KW - PARTON DISTRIBUTIONS

KW - QCD

KW - HADRON COLLIDERS

KW - LHC

KW - PAIR PRODUCTION

KW - POLARIZATION

UR - http://www.scopus.com/inward/record.url?scp=85037716065&partnerID=8YFLogxK

U2 - 10.1007/JHEP12(2017)017

DO - 10.1007/JHEP12(2017)017

M3 - Article

AN - SCOPUS:85037716065

VL - 2017

JO - Journal of High Energy Physics

JF - Journal of High Energy Physics

SN - 1029-8479

IS - 12

M1 - 17

ER -

ID: 9868327