The fully differential single-top-quark cross section in next-to-leading order QCD

TL;DR

The paper develops and cross-validates three independent NLO QCD methods—two-cutoff phase-space slicing, one-cutoff slicing, and massive dipole subtraction—to produce fully differential predictions for single-top-quark production in the s- and t-channels, including spin information via helicity amplitudes. It demonstrates cancellation of infrared divergences and cutoff independence, provides updated cross sections with modern PDFs, and shows consistency across calculations with realistic jet definitions and cuts. This work enhances the precision of top-quark weak-interaction studies and improves modeling of backgrounds for Higgs and new-physics searches.

Abstract

We present a new next-to-leading order calculation for fully differential single-top-quark final states. The calculation is performed using phase space slicing and dipole subtraction methods. The results of the methods are found to be in agreement. The dipole subtraction method calculation retains the full spin dependence of the final state particles. We show a few numerical results to illustrate the utility and consistency of the resulting computer implementations.

Figures (8)

• Figure 1: The leading order Feynman diagrams for reactions given in (a) Eq. \ref{['eq:3']} and (b) Eq. \ref{['eq:6']}. The top quark line is doubled.
• Figure 2: The one-loop virtual corrections to the (a) $t$-channel and (b) $s$-channel amplitudes.
• Figure 3: The next-to-leading order single-top-quark total cross section for the $s$-channel at a $\sqrt{S}=2$ TeV proton-antiproton machine. The two- and three- body contributions, together with their sum, are shown as a function of the soft cutoff $\delta_s$. The bottom enlargement shows the sum (open circles) relative to $\pm 5 \%$ (dotted lines) of the analytic result (solid line).
• Figure 4: The next-to-leading order single-top-quark total cross section for the $t$-channel at a $\sqrt{S}=2$ TeV proton-antiproton machine. The two- and three- body contributions, together with their sum, are shown as a function of the soft cutoff $\delta_s$. The bottom enlargement shows the sum (open circles) relative to $\pm 5\%$ (dotted lines) of the analytic result (solid line).
• Figure 5: Transverse momentum distribution of the $b$-jet at NLO in $s$-channel production of a top quark at the Tevatron ($\sqrt{S}= 2$ TeV) after cuts. Phase space slicing (PSS) results (solid) and massive dipole formalism (MDF) results (dashed) are both shown.