Theory of ultrasonic attenuation in impure anisotropicp-wave superconductors

The longitudinal ultrasonic attenuation for impure anisotropic superconductors in the axial and polar phases is calculated using the deformation-potential approach. Impurity effects are treated by the self-consistent Born method. For realistic values of ql and ωτ, good agreement is obtained between theory and experiments. This is the case for the exponents describing the intermediate temperature dependence as well as the peak observed in the sound attenuation just below $T_c$. The behavior of the peak that is calculated in this theory is examined and discussed.