Search for anomalous couplings in the Wtb vertex from the measurement of double differential angular decay rates of single top quarks produced in the t-channel with the ATLAS detector

Mullier, Geoffrey; Haug, Sigve; Weber, Michael; Meloni, Federico; Cervelli, Alberto; Beck, Hans Peter; Stucci, Stefania; Ereditato, Antonio (2016). Search for anomalous couplings in the Wtb vertex from the measurement of double differential angular decay rates of single top quarks produced in the t-channel with the ATLAS detector. Journal of High Energy Physics, 2016(4), pp. 1-46. Springer 10.1007/JHEP04(2016)023

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The electroweak production and subsequent decay of single top quarks is determined by the properties of the Wtb vertex. This vertex can be described by the complex parameters of an effective Lagrangian. An analysis of angular distributions of the decay products of single top quarks produced in the t-channel constrains these parameters simultaneously. The analysis described in this paper uses 4.6 fb⁻¹ of proton-proton collision data at √s=7 TeV collected with the ATLAS detector at the LHC.Two parameters are measured simultaneously in this analysis. The fraction f₁ of decays containing transversely polarised W bosons is measured to be 0.37±0.07 (stat.⊕ syst.). The phase δ_ between amplitudes for transversely and longitudinally polarised W bosons recoiling against left-handed b -quarks is measured to be −0.14π±0.036π (stat.⊕ syst.).The correlation in the measurement of these parameters is 0.15 . These values result in two-dimensional limits at the 95% confidence level on the ratio of the complex coupling parameters gR and VL, yielding Re [gR /VL] ∈ [−0.36,0.10] and Im [gR /VL] ∈ [−0.17,0.23] with a correlation of 0.11. The results are in good agreement with the predictions of the Standard Model.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Laboratory for High Energy Physics (LHEP)

UniBE Contributor:

Haug, Sigve; Weber, Michael and Beck, Hans Peter

Subjects:

500 Science > 530 Physics
500 Science > 510 Mathematics

ISSN:

1029-8479

Publisher:

Springer

Language:

English

Submitter:

Annette Krebs-Wegenast

Date Deposited:

15 Aug 2017 09:45

Last Modified:

20 Aug 2017 02:17

Publisher DOI:

10.1007/JHEP04(2016)023

Additional Information:

Kollaboration - Es sind nur die Berner Autoren namentlich erwähnt.

BORIS DOI:

10.7892/boris.100010

URI:

https://boris.unibe.ch/id/eprint/100010

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