Measurements of top-quark pair to Z-boson cross-section ratios at √s =13, 8, 7 TeV with the ATLAS detector

Allbrooke, B M M, Asquith, L, Cerri, A, Chavez Barajas, C A, De Santo, A, Salvatore, F, Santoyo Castillo, I, Suruliz, K, Sutton, M R, Vivarelli, I and The ATLAS Collaboration, (2017) Measurements of top-quark pair to Z-boson cross-section ratios at √s =13, 8, 7 TeV with the ATLAS detector. Journal of High Energy Physics, 2017 (2). a117. ISSN 1126-6708

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Abstract

Ratios of top-quark pair to Z-boson cross sections measured from proton-proton collisions at the LHC centre-of-mass energies of s√=13TeV, 8TeV, and 7TeV are presented by the ATLAS Collaboration. Single ratios, at a given √s for the two processes and at different √s for each process, as well as double ratios of the two processes at different √s , are evaluated. The ratios are constructed using previously published ATLAS measurements of the tt¯ and Z-boson production cross sections, corrected to a common phase space where required, and a new analysis of Z → ℓ+ℓ− where ℓ = e, μ at s√=13 TeV performed with data collected in 2015 with an integrated luminosity of 3.2 fb−1. Correlations of systematic uncertainties are taken into account when evaluating the uncertainties in the ratios. The correlation model is also used to evaluate the combined cross section of the Z → e+e− and the Z → μ+μ− channels for each √s value. The results are compared to calculations performed at next-to-next-to-leading-order accuracy using recent sets of parton distribution functions. The data demonstrate significant power to constrain the gluon distribution function for the Bjorken-x values near 0.1 and the light-quark sea for x < 0.02.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups: Experimental Particle Physics Research Group
Subjects: Q Science > QC Physics
Depositing User: Billy Wichaidit
Date Deposited: 13 Jul 2017 15:53
Last Modified: 13 Jul 2017 16:01
URI: http://sro.sussex.ac.uk/id/eprint/69250

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Project NameSussex Project NumberFunderFunder Ref
ATLASG0275STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCILST/I006048/1