Scattering Theory on Locally Symmetric Spaces

Abstract

In 1977, Victor Guillemin published a paper discussing geometric scattering theory, in which he related the Lax-Phillips Scattering matrices (associated to a noncompact hyperbolic surface with cusps) and the sojourn times associated to a set of geodesics which run to infinity in either direction.

This work was later extended to Q-rank one Locally symmetric spaces coming from Semisimple Liegroups by Lizhen Ji and Maciej Zworski.

In this thesis, we will extend some of the above mentioned results to higher rank locally symmetric spaces, in particular we will introduce higher dimensional analogues of scattering geodesics called Scattering Flat and study these flats in the case of the locally symmetric space given by the quotient SL(3;Z)SL(3;R)/SO(3). A parametrization space is discussed for such scattering flats as well as an associated vector valued parameter (bearing similarities to sojourn times) called sojourn vector and these are related to the frequency of oscillations of the associated scattering matrices coming from the minimal parabolic subgroups of SL(3;R). The key technique is the factorization of higher rank scattering matrices.