Constraining dimension-6 SMEFT with higher-order predictions for $p p \to t W$

TL;DR

This paper investigates single-top production with a W boson at the LHC to constrain dimension-6 SMEFT operators, incorporating higher-order QCD corrections and detailed uncertainty analysis.

Contribution

It provides the first comprehensive analysis of SMEFT effects in this process at NLO and approximate NNLO, including uncertainty quantification and sensitivity estimates.

Findings

Effective scales up to 2 TeV can be probed in nonmarginalized fits.

Marginalized fits reach sensitivities around 0.5 to 1.5 TeV.

Higher-order QCD corrections improve the precision of SMEFT constraints.

Abstract

We study single-top production in association with a $W$ boson at the Large Hadron Collider (LHC) as a probe of dimension-6 Standard Model effective field theory (SMEFT) at leading order, next-to-leading order, and approximate next-to-next-to-leading order accuracy in quantum chromodynamics (QCD). The process is sensitive to operators that modify the top-quark weak and chromomagnetic dipole interactions, and we perform three-parameter linear and quadratic SMEFT fits using doubly differential top-quark distributions in transverse momentum and rapidity for the Run II and Run III configurations at the LHC. We provide a detailed account of the uncertainties and quantify the impact of the different uncertainty components across bins and perturbative orders. We find that effective scales up to 2 TeV can be probed in nonmarginalized fits, while in marginalized fits the corresponding scales are around 0.5 and 1.5 TeV for linear and quadratic fits, respectively.