QCD corrections to t\bar t b \bar b productions via photon-photon collisions at linear colliders

TL;DR

This paper presents a detailed calculation of next-to-leading order QCD corrections to top-antitop-bottom-antibottom production in photon-photon collisions at linear colliders, showing significant effects on cross sections and distributions.

Contribution

It provides the first complete NLO QCD correction calculation for this process, including hexagon and pentagon amplitude evaluations, and analyzes their impact on cross sections and kinematic distributions.

Findings

NLO QCD corrections increase the LO cross section significantly.

The K-factor decreases from 1.70 to 1.14 as energy increases from 400 GeV to 2 TeV.

Corrections improve the stability of the cross section against renormalization scale variations.

Abstract

We calculated the complete next-to-leading order(NLO) QCD corrections to the $t\bar t b \bar b$ production process at a $\gamma \gamma$ collider in the standard model(SM). The calculation of the one-loop QCD correction includes the evaluations of the hexagon and pentagon amplitudes. We studied the NLO QCD corrected total cross section, the distributions of transverse momenta of final top- and bottom-quark states, and the dependence of the cross section on renormalization scale $\mu$. It shows that NLO QCD correction generally increases the LO cross section in our chosen parameter space, and the K-factor varies from 1.70 to 1.14 when colliding energy goes up from $400 GeV$ to $2 TeV$. We find that the correction distinctly changes the distributions of transverse momenta of the final top- and bottom-quark states, and the NLO QCD correction obviously improves the independence of the cross section for process $\gamma\gamma \to t\bar t b\bar b$ on the renormalization scale.