G. Bevilacqua
Precise predictions for tt¯γ/tt¯ cross section ratios at the LHC
Bevilacqua, G.; Hartanto, H.B.; Kraus, M.; Weber, T.; Worek, M.
Authors
H.B. Hartanto
M. Kraus
T. Weber
M. Worek
Abstract
With the goal of increasing the precision of NLO QCD predictions for the pp→tt¯γ process in the di-lepton top quark decay channel we present theoretical predictions for the R=σtt¯γ/σtt¯ cross section ratio. Results for the latter together with various differential cross section ratios are given for the LHC with the Run II energy of s√=13 TeV. Fully realistic NLO computations for tt¯ and tt¯γ production are employed. They are based on matrix elements for e+νeμ−ν¯¯¯μbb¯¯ and e+νeμ−ν¯¯¯μbb¯¯γ processes and include all resonant and non-resonant diagrams, interferences, and off-shell effects of the top quarks and the W gauge bosons. Various renormalisation and factorisation scale choices and parton density functions are examined to assess their impact on the cross section ratio. Depending on the transverse momentum cut on the hard photon a judicious choice of a dynamical scale allows us to obtain 1%–3% percent precision on R . Moreover, for differential cross section ratios theoretical uncertainties in the range of 1%-6% have been estimated. Until now such high precision predictions have only been reserved for the top quark pair production at NNLO QCD. Thus, R at NLO in QCD represents a very precise observable to be measured at the LHC for example to study the top quark charge asymmetry or to probe the strength and the structure of the t- t¯ -γ vertex. The latter can shed some light on possible new physics that can reveal itself only once sufficiently precise theoretical predictions are available.
Citation
Bevilacqua, G., Hartanto, H., Kraus, M., Weber, T., & Worek, M. (2019). Precise predictions for tt¯γ/tt¯ cross section ratios at the LHC. Journal of High Energy Physics, 2019(1), Article 188. https://doi.org/10.1007/jhep01%282019%29188
Journal Article Type | Article |
---|---|
Online Publication Date | Jan 24, 2019 |
Publication Date | Jan 24, 2019 |
Deposit Date | Jan 31, 2019 |
Publicly Available Date | Jan 31, 2019 |
Journal | Journal of High Energy Physics |
Print ISSN | 1126-6708 |
Publisher | Scuola Internazionale Superiore di Studi Avanzati (SISSA) |
Peer Reviewed | Peer Reviewed |
Volume | 2019 |
Issue | 1 |
Article Number | 188 |
DOI | https://doi.org/10.1007/jhep01%282019%29188 |
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This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.
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