\begin{table}%t4
%\centering
\par
\caption{\label{tabNep}Fitting coefficients for Eq.~(\ref{zetaNep}) for CR protons (p, also including heavy nuclei) and electrons (e).}
\begin{tabular}{llll}
\hline\hline
$k$ & spectrum   & $\zeta_{0,k}$        & $a$  \\
    &            & (s$^{-1}$)           &      \\
\hline\noalign{\smallskip}
p  & W98        & $2.0\times 10^{-17}$ & $0.021$ \\
p  & M02        & $6.8\times 10^{-16}$ & $0.423$ \\
\hline\noalign{\smallskip}
e   & C00      & $1.4\times 10^{-19}$ & $0.040$ \\
e   & E00      & $2.6\times 10^{-14}$ & $0.805$ \\
\hline
\end{tabular}
\end{table}