QCD corrections to the production of $t\bar{t}\gamma$ at the ILC

TL;DR

This paper calculates the one-loop QCD corrections to top quark pair production with a photon at the ILC, revealing significant K-factors and analyzing distributions and asymmetries to test the top quark's electroweak properties.

Contribution

It provides the first detailed NLO QCD correction analysis for $tar{t}\gamma$ production at the ILC, including distributions and asymmetries.

Findings

K-factor up to 1.238 at 500 GeV

Top quark forward-backward asymmetry around 45-56%

Transverse momentum distributions at LO and NLO

Abstract

A precise calculation of the top quark pair production associated with a hard photon is essential for testing the electroweak property of the top quark in the Standard Model (SM). We investigate the one-loop QCD corrections to the process $e^{+}e^{-} \to t\bar{t}\gamma$ at the International Linear Collider (ILC), and find that the $K$-factor can be as large as 1.238 (1.105, 1.060) for a center-of-mass energy $\sqrt{s}=500 (800, 1500)$ GeV. The transverse momentum distributions of the top quark and photon are respectively shown at leading order (LO) and next-to-leading order(NLO). Due to the asymmetric rapidity distribution of the top (anti-top) quark, we also study the top quark forward-backward asymmetry ($A^{t}_{FB}$) in $t\bar{t}\gamma$ production at NLO, which is found to be 45.82 (55.25, 55.89)% for $\sqrt{s}=500 (800, 1500)$ GeV.