SMEFT everywhere: a NLO study of $\mathbf{pp}\to \mathbf{t}\bar{\mathbf{t}}\mathbf{H}$ with decaying tops

Abstract

We present the computation of the next-to-leading order QCD corrections to the $pp\to t\bar{t}H+X$ process in the di-lepton channel at the LHC, including relevant dimension-6 operators $({\mathcal{O}}_{t\varphi },{\mathcal{O}}_{\varphi G},{\mathcal{O}}_{tG},{\mathcal{O}}_{tW})$ from the Standard Model Effective Field Theory. In our studies, higher-order corrections and effective operators are consistently included in the production part of the process as well as in the top-quark decays. We perform a detailed study of linear, cross, and quadratic contributions and their uncertainties, including renormalisation group effects. Our findings are presented at the integrated and differential cross-section level for the LHC Run III center-of-mass energy of $\sqrt{s}=13.6$ TeV. Finally, we provide predictions for $pp\to t\bar{t}H+X$ with stable top quarks and compare them with the results in which top quarks are reconstructed from their decay products. We show that kinematic cuts, as well as higher-order effects and SMEFT operators in top-quark decays, are important and should be consistently considered together, because they have a significant impact on the shape of the standard observables measured for the $pp\to t\bar{t}H+X$ process at the LHC.

Comments: 46 pages, 22 figures, and 8 tables, a few typos corrected, citations added