Journal of High Energy Physics > 2017 > 2017 > 2 > 1-54
Measurements of top-quark pair to Z-boson cross-section ratios at s = 13 $$ \sqrt{s}=13 $$ , 8, 7 TeV with the ATLAS detector
Source
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 = 13 $$ \sqrt{s}=13 $$ TeV, 8 TeV, and 7 TeV are presented by the ATLAS Collaboration. Single ratios, at a given s $$ \sqrt{s} $$ for the two processes and at different s $$ \sqrt{s} $$ for each process, as well as double ratios of the two processes at different s $$ \sqrt{s} $$ , are evaluated. The ratios are constructed using previously published ATLAS measurements of the t t ¯ $$ t\overline{t} $$ 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 $$ \sqrt{s}=13 $$ 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 $$ \sqrt{s} $$ 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.
Identifiers
journal e-ISSN : | 1029-8479 |
DOI | 10.1007/JHEP02(2017)117 |
Authors
The ATLAS collaboration
- University Politehnica Bucharest, Bucharest, Romania
- Centre National de l’Energie des Sciences Techniques Nucleaires, Rabat, Morocco
- Universidade Nova de Lisboa, Dep Fisica and CEFITEC of Faculdade de Ciencias e Tecnologia, Caparica, Portugal
- CERN, Geneva 23, Switzerland
B. Abbott
- University of Oklahoma, Homer L. Dodge Department of Physics and Astronomy, Norman, U.S.A.