23.26 fit \(a\) from perturbative expansion

\[\begin{gather} \chi^2/d.o.f.=1.46481 \\ P[0]=-0.834662\pm (0.0094) \\ \end{gather}\] {\[\begin{gather} C=\begin{pmatrix} 8.87e-05\\ \end{pmatrix} \end{gather}\]}