Anisotropy dissipation in brane-world inflation - art. no. 063509

We examine the behavior of an anisotropic brane-world in the presence of in flationary scalar fields. We show that. contrary to naive expectations, a l arge anisotropy does not adversely affect inflation. On the contrary, a lar ge initial anisotropy introduces more damping into the scaler field equatio n of motion, resulting in greater inflation. The rapid decay of anisotropy in the brane-world significantly increases the class of initial conditions from which the observed universe could have originated. This generalizes a similar result in general relativity. A unique feature of Bianchi type I br ane-world cosmology appears to be that for scalar fields with a large kinet ic term the initial expansion of the Universe is quasi-isotropic. The Unive rse grows more anisotropic during an intermediate transient regime until an isotropy finally disappears during inflationary expansion.