\newcommand{\mt}{m_t}
\newcommand{\zm}{{\zeta}^{-1}}
\newcommand{\zz}{{\zeta}^2}
\newcommand{\zd}{{\zeta}^3}
\newcommand{\pee}{P_e}
\newcommand{\pez}{\tilde{P}_e}
\newcommand{\pge}{P_{\gamma}}
\newcommand{\pgse}{P_{{\gamma}'}}
\newcommand{\pgz}{\tilde{P}_{\gamma}}
\newcommand{\pgsz}{\tilde{P}_{{\gamma}'}}
\newcommand{\eplus}{e^{+}}
\newcommand{\eminus}{e^{-}}
\newcommand{\lgg}{\frac{dL}{dz}}
\newcommand{\lggk}{\frac{1}{k^2 L_{ee}}\frac{L_{\gamma\gamma}(z)}{dz}}
\newcommand{\esn}{^{1}\! S_0}
\newcommand{\wurzel}{\sqrt{1-\frac{4 m_t^2}{s}}}
\newcommand{\sgg}{{\sigma}_{\gamma\gamma\rightarrow t\bar{t}}}
\newcommand{\fggn}{f^{(0)}_{\gamma\gamma}}
\newcommand{\fgge}{f^{(1)}_{\gamma\gamma}}
\newcommand{\muq}{{\mu}^2}
\newcommand{\nf}{n_f}
\newcommand{\lms}{{\Lambda}_{\overline{MS}}}
\newcommand{\lmsq}{{\Lambda}^2_{\overline{MS}}}
\newcommand{\dse}{^{3}\! S_1}


