Radiative Corrections to $\gamma \gamma \to t\bar{t}$ in the Electroweak Standard Model

Abstract

The cross-section for $\gamma \gamma \to t\bar{t}$ with arbitrary polarized photons is calculated within the electroweak Standard Model including the complete virtual and soft-photonic $O(\alpha )$ corrections. We present a detailed numerical discussion of the radiative corrections with particular emphasis on the purely weak corrections. These are usually of the order of 1--10\% for energies up to 1 TeV. For unpolarized or equally polarized photons they reach almost 10\% close to threshold. The large corrections cannot be traced back to a universal origin like the running of $\alpha$ or the $\rho$-parameter. Apart from the energy region around the Higgs resonance $(\gamma \gamma \to H^{\ast }\to t\bar{t})$ the weak corrections are widely independent of the Higgs-boson mass.

Comments: 22 pages, LaTeX (compressed, uuencoded), 20 figures as compressed uuencoded ps-files, complete ps-file available via anonymous ftp from ftp://ftp.physik.uni-wuerzburg.de/pub/preprint/WUE-ITP-95-017.ps