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

TL;DR

This paper uses advanced Fourier analysis of angular decay rates in single top-quark events at 13 TeV to tightly constrain effective field theory operators, testing for deviations from the Standard Model.

Contribution

It introduces a novel Fourier-based analysis method applied to quadruple-differential decay rates to improve sensitivity to EFT operators in top-quark processes.

Findings

Wilson coefficients are tightly constrained.

Results are compatible with Standard Model predictions.

Enhanced sensitivity to top-quark decay and production vertices.

Abstract

Events with $t$-channel single top quarks are used to probe effective field theory operators in $\sqrt{s}=13$ TeV proton-proton collision data corresponding to 140 fb$^{-1}$ recorded by the ATLAS detector at the Large Hadron Collider. An analysis method leveraging Fourier techniques applied to quadruple-differential decay rates based on observables containing angular information about the decays of the top quarks is used to achieve high sensitivity. 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.