Testing parton distribution functions with t-channel single-top-quark production

TL;DR

This paper investigates how t-channel single-top-quark production can serve as a tool to test and improve parton distribution functions, highlighting the importance of b-quark mass uncertainties in theoretical predictions.

Contribution

It introduces novel consistency checks for PDFs using single-top-quark production data and emphasizes the need to better account for b-quark mass uncertainties in PDF fits.

Findings

Single-top-quark production constrains PDFs through DDIS form.

Current treatment of b-quark mass uncertainty is inadequate.

B-quark mass uncertainty dominates the theoretical error for this process.

Abstract

The production of single top-quarks in the t-channel at hadron colliders imposes strong analytic constraints on parton distribution functions (PDFs) through its double deeply inelastic scattering (DDIS) form. We exploit this to provide novel consistency checks between LO, NLO and NNLO PDF fits and propose to include it as a constraint in future PDF fits. Furthermore, while it is well-known that the b-quark PDF is highly sensitive to the b-quark mass, we show that the treatment of this systematic uncertainty is still incomplete, fragmented or outright missing at the moment. Consequently, we conclude that the b-quark mass uncertainty is the dominant but so far broadly neglected theory uncertainty for this process.