Final state QCD corrections to off-shell single top production in hadron collisions

TL;DR

The paper tackles final-state QCD radiative corrections to off-shell single-top production with subsequent decays in hadron collisions, where final-state radiation can distort the invariant-mass distribution used to reconstruct the top. It implements an exact one-loop QCD calculation of the final-state corrections to the signal diagram (with initial-state effects treated separately) and assesses the validity of the narrow width approximation by comparison. A key finding is that final-state radiation distorts the tree-level Breit-Wigner distribution of the top invariant mass while leaving the peak position unchanged, and that the exact one-loop result agrees with the narrow width approximation for the cross section, hadronic transverse energy distribution, and bottom-lepton invariant mass distribution. These results provide precise predictions for experiments in the semi-leptonic channel and support the reliability of the narrow width framework for these observables, with implications for top-quark analyses and potential new-physics scenarios in W-like production channels.

Abstract

In this paper, I study final state QCD radiative corrections to off-shell single top production via decaying $W$ at hadron collider energies. The tree level Breit-Wigner distribution of the produced top invariant mass is distorted by final state QCD radiation, while the peak position remains unchanged. The exact one loop QCD calculation and the narrow width approximation agree in predicting the cross section, the hadronic transverse energy distribution and the bottom-lepton invariant mass distribution.