Spherical functions for small -types
arXiv:1710.02975
Abstract
For a connected semisimple real Lie group of non-compact type, Wallach introduced a class of -types called small. We classify all small -types for all simple Lie groups and prove except just one case that each elementary spherical function for each small -type can be expressed as a product of hyperbolic cosines and a Heckman-Opdam hypergeometric function. As an application, the inversion formula for the spherical transform on is obtained from Opdam's theory on hypergeometric Fourier transforms.
43 pages