Double cosets for $\SU(2)\times...\times\SU(2)$ and outer automorphisms of free groups
arXiv:0903.4767
Abstract
Consider the space of double cosets of the product of copies of $\SU(2)$ with respect to the diagonal subgroup. We get a parametrization of this space, the radial part of the Haar measure, and explicit formulas for the actions of the group of outer automorphisms of the free group and of the braid group of strings.
arXiv comment14pp, some typos are removed