  This paper describes an analytical method to calculate the emittance growth
rates due to intra-beam scattering in a circular accelerator with arbitrary x-y
coupling. The underlying theory is based on the Landau collision integral and
the extended Mais-Ripken parametrization of a coupled betatron motion. The
presented results are based on calculations of average emittance growth rates
for an initially Gaussian distribution. They are applicable to both bunched and
continuous beams.
