Constraints on effective field theories via quadruple-differential angular decay rates from t-channel single-top-quark production at √s=13 TeV with the ATLAS detector

A bstract Events with t -channel single top quarks are used to probe effective field theory operators in √s=13 s = 13 TeV proton–proton collision data corresponding to 140 fb − 1 recorded by the ATLAS detector at the Large Hadron Collider. To extract a maximum amount of information from these events, the joint fourfold probability distribution for four kinematic angles is simultaneously analysed. A method leveraging Fourier techniques to handle the challenges arising from this approach is employed. The relevant effective field theory operators are those sensitive to top-quark decay and t -channel production vertices. Their Wilson coefficients are tightly constrained, with results compatible with Standard Model predictions.