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

M. Aaboud; G. Aad; B. Abbott; J. Abdallah; O. Abdinov; B Abeloos; O.S. AbouZeid; NL Abraham; H. Abramowicz; H. Abreu; R. Abreu; Y. Abulaiti; S. Acharya; Shin-ichi Adachi; L. Adamczyk; J P Adelman; M. Adersberger; T. Adye; A. A. Affolder; Mogens Dam; Jørn Dines Hansen; Jørgen Beck Hansen; Peter Henrik Hansen; Troels Christian Petersen; James William Monk; Lars Egholm Pedersen; Graig Wiglesworth; Gorm Aske Gram Krohn Galster; Simon Holm Stark; Geert-Jan Besjes; Flavia de Almeida Dias; Stefania Xella; Milena Bajic

doi:10.1007/JHEP12(2017)017

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

M. Aaboud, G. Aad, B. Abbott, J. Abdallah, O. Abdinov, B Abeloos, O.S. AbouZeid, NL Abraham, H. Abramowicz, H. Abreu, R. Abreu, Y. Abulaiti, S. Acharya, Shin-ichi Adachi, L. Adamczyk, J P Adelman, M. Adersberger, T. Adye, A. A. Affolder, Mogens DamJørn Dines Hansen, Jørgen Beck Hansen, Peter Henrik Hansen, Troels Christian Petersen, James William Monk, Lars Egholm Pedersen, Graig Wiglesworth, Gorm Aske Gram Krohn Galster, Simon Holm Stark, Geert-Jan Besjes, Flavia de Almeida Dias, Stefania Xella, Milena Bajic

Experimental Particle Physics

11 Citations (Scopus)

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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 [g_R/V_L ∈ [−0.12, 0.17] and Im [g_R/V_L ∈ [−0.07, 0.06]. Constraints are also placed on the ratios |V_R/V_L| and |g_L/V_L|. 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.[Figure not available: see fulltext.].

Original language	English
Article number	017
Journal	Journal of High Energy Physics
Volume	2017
Issue number	12
Pages (from-to)	1-59
Number of pages	59
ISSN	1126-6708
DOIs	https://doi.org/10.1007/JHEP12(2017)017
Publication status	Published - 1 Dec 2017

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Aaboud, M., Aad, G., Abbott, B., Abdallah, J., Abdinov, O., Abeloos, B., AbouZeid, O. S., Abraham, NL., Abramowicz, H., Abreu, H., Abreu, R., Abulaiti, Y., Acharya, S., Adachi, S., Adamczyk, L., Adelman, J. P., Adersberger, M., Adye, T., Affolder, A. A., ... Bajic, M. (2017). Analysis of the Wtb vertex from the measurement of triple-differential angular decay rates of single top quarks produced in the t-channel at root s=8 TeV with the ATLAS detector. Journal of High Energy Physics, 2017(12), 1-59. Article 017. https://doi.org/10.1007/JHEP12(2017)017

Analysis of the Wtb vertex from the measurement of triple-differential angular decay rates of single top quarks produced in the t-channel at root s=8 TeV with the ATLAS detector. / Aaboud, M.; Aad, G.; Abbott, B. et al.
In: Journal of High Energy Physics, Vol. 2017, No. 12, 017, 01.12.2017, p. 1-59.

Research output: Contribution to journal › Journal article › Research › peer-review

Aaboud, M, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Abeloos, B, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, S, Adachi, S, Adamczyk, L, Adelman, JP, Adersberger, M, Adye, T, Affolder, AA, Dam, M , Hansen, JD , Hansen, JB , Hansen, PH , Petersen, TC, Monk, JW, Pedersen, LE, Wiglesworth, G, Galster, GAGK, Stark, SH, Besjes, G-J, de Almeida Dias, F, Xella, S & Bajic, M 2017, 'Analysis of the Wtb vertex from the measurement of triple-differential angular decay rates of single top quarks produced in the t-channel at root s=8 TeV with the ATLAS detector', Journal of High Energy Physics, vol. 2017, no. 12, 017, pp. 1-59. https://doi.org/10.1007/JHEP12(2017)017

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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 root 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.[Figure not available: see fulltext.].",

author = "M. Aaboud and G. Aad and B. Abbott and J. Abdallah and O. Abdinov and B Abeloos and O.S. AbouZeid and NL Abraham and H. Abramowicz and H. Abreu and R. Abreu and Y. Abulaiti and S. Acharya and Shin-ichi Adachi and L. Adamczyk and Adelman, {J P} and M. Adersberger and T. Adye and Affolder, {A. A.} and Mogens Dam and Hansen, {J{\o}rn Dines} and Hansen, {J{\o}rgen Beck} and Hansen, {Peter Henrik} and Petersen, {Troels Christian} and Monk, {James William} and Pedersen, {Lars Egholm} and Graig Wiglesworth and Galster, {Gorm Aske Gram Krohn} and Stark, {Simon Holm} and Geert-Jan Besjes and {de Almeida Dias}, Flavia and Stefania Xella and Milena Bajic",

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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 root s=8 TeV with the ATLAS detector

AU - Aaboud, M.

AU - Aad, G.

AU - Abbott, B.

AU - Abdallah, J.

AU - Abdinov, O.

AU - Abeloos, B

AU - AbouZeid, O.S.

AU - Abraham, NL

AU - Abramowicz, H.

AU - Abreu, H.

AU - Abreu, R.

AU - Abulaiti, Y.

AU - Acharya, S.

AU - Adachi, Shin-ichi

AU - Adamczyk, L.

AU - Adelman, J P

AU - Adersberger, M.

AU - Adye, T.

AU - Affolder, A. A.

AU - Dam, Mogens

AU - Hansen, Jørn Dines

AU - Hansen, Jørgen Beck

AU - Hansen, Peter Henrik

AU - Petersen, Troels Christian

AU - Monk, James William

AU - Pedersen, Lars Egholm

AU - Wiglesworth, Graig

AU - Galster, Gorm Aske Gram Krohn

AU - Stark, Simon Holm

AU - Besjes, Geert-Jan

AU - de Almeida Dias, Flavia

AU - Xella, Stefania

AU - Bajic, Milena

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.[Figure not available: see fulltext.].

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.[Figure not available: see fulltext.].

U2 - 10.1007/JHEP12(2017)017

DO - 10.1007/JHEP12(2017)017

M3 - Journal article

SN - 1126-6708

VL - 2017

SP - 1

EP - 59

JO - Journal of High Energy Physics

JF - Journal of High Energy Physics

IS - 12

M1 - 017

ER -

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

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