\[\widehat{c}(\kappa,\mu)=\sqrt{2\pi}\kappa^{\frac{1}{6}}\left(\frac{\kappa-\mu}%
{\kappa+\mu}\right)^{\frac{1}{2}\mu}\left(\frac{e^{2}}{\kappa^{2}-\mu^{2}}%
\right)^{\frac{1}{2}\kappa},\]