The Spin Diffusion Coefficient of Superfluid $^{3}$He in the A$_{1}$- phase

Using the Boltzmann kinetic approach and perturbation theory, an approximate expression describing the variation with temperature, of the spin diffusion coefficient in the A$_{1}$-phase of $^{3}$He is derived. It is observed that for temperatures close to the transition temperature T$_{c}$, the spin diffusion coefficient D $\sim $ (T$_{c }$-- T)$^{1/2}$ + \textit{const}. Comparison of the theoretical result with related experimental measurements is discussed.