2026/07/29 by Gauthier Durieux, Hesham El Faham, Rikkert Frederix +2
Physics and Astronomy · #hep-ph #hep-ex
23 pages, 14 figures, 1 table
arxiv created 2026/07/29 · arxiv updated 2026/07/31
In measurements of four-top-quark production (tttt), LHC collaborations observe a significant degeneracy with three-top-quark production. We compute the dominant three-top-production mode, namely associated production with a W boson (tttW), at complete next-to-leading order (NLO), including all possible QCD and electroweak (EW) corrections. Beyond leading order (LO), tttW production with the radiation of an additional b-flavoured quark contributes to the same final state as tttt production with a t → bW decay. Away from the on-shell top-quark limit, the usual overlap removal of resonant contributions in the non-resonant computation either breaks gauge invariance and generates unitarity violation or involves a significant arbitrariness in the required reshuffling of momenta. To overcome these issues, we introduce a novel window-removal prescription that produces consistent predictions for the inseparable tttW+tttt process, with both components described at NLO accuracy. We argue that such a joint prediction should be used in comparisons with experimental selections targeting tttt production, since the on-shell tttt component can not be isolated in practice. Such a joint prediction has an inclusive rate more than 10% higher than the purely on-shell tttt one. We also study an idealised veto on additional hard and central b-jet radiation, which suppresses the contributions of resonant tttt diagrams as well as their interference with non-resonant tttW ones and therefore defines a relatively pure tttW-like signal region. Formally subleading coupling orders are numerically important at LO, while the corresponding subleading NLO corrections largely cancel both inclusively and differentially. Consequently, the complete-NLO prediction is well approximated by retaining the first three LO coupling orders together with the leading QCD NLO correction.