Universality of Low Energy Absorption Cross Sections for Black Holes

In this paper we compute the low energy absorption cross section for minimally coupled massles scalars and spin- $1/2$ particles into a general spherically symmetric black hole in arbitrary dimensions. The scalars have a cross section equal to the area of the black hole, while the spin- $1/2$ particles give the area measured in a flat spatial metric conformally related to the true metric.