Equation 12.23.248EE58E16325

\begin{equation} \begin{split} \Xi _{\rm down}(s)& =\left(\frac{s}{1+s}\right)^ m,\\ \Xi _{\rm up}(s)& =\frac{\left(1+\frac{s}{1+s}\right)^ m-1}{2^ m-1}. \end{split} \end{equation}