Radiative corrections to γγ→<i>tt¯</i>in the electroweak standard model

Abstract

The cross section for \ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\rightarrow}tt\ifmmode\bar\else\textasciimacron\fi{} with arbitrary polarized photons is calculated within the electroweak standard model including the complete virtual and soft-photonic O(\ensuremath{\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 such as the running of \ensuremath{\alpha} or the \ensuremath{\rho} parameter. Apart from the energy region around the Higgs resonance (\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\rightarrow}${\mathit{H}}^{\mathrm{*}}$\ensuremath{\rightarrow}tt\ifmmode\bar\else\textasciimacron\fi{}) the weak corrections are widely independent of the Higgs-boson mass. \textcopyright{} 1995 The American Physical Society.