Analysis of the Wtb vertex from the measurement of triple-differential angular decay rates of single top quarks produced in the t-channel at $\sqrt{s}=8$ TeV with the ATLAS detector
PBN-AR
Instytucja
Wydział Fizyki i Informatyki Stosowanej (Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie)
Informacje podstawowe
Główny język publikacji
EN
Czasopismo
Journal of High Energy Physics (40pkt w roku publikacji)
ISSN
1126-6708
EISSN
1029-8479
Wydawca
Springer
DOI
Rok publikacji
2017
Numer zeszytu
12 art. no. 017
Strony od-do
1--60
Numer tomu
Link do pełnego tekstu
Identyfikator DOI
Liczba arkuszy
4.3
Słowa kluczowe
EN
electroweak interaction
top physics
Hadron-Hadron scattering (experiments)
Streszczenia
Język
EN
Treść
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 f(1) = 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 delta = 0.002 pi(+0.016 pi)(+0.017 pi), 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 [g(R)/V-L is an element of [-0.12, 0.17] and Im [g(R)/V-L is an element of [-0.07, 0.06]. Constraints are also placed on the ratios vertical bar V-R/V-L vertical bar and vertical bar g(L)/V-L vertical bar. 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.
Cechy publikacji
original article
peer-reviewed
Inne
System-identifier
idp:111604
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