A Generalized Weil Representation for the Finite Split Orthogonal Group O(q;2n,2n), q odd and larger than 3

Abstract

\def\F{{\Bbb F}} We construct via generators and relations a generalized Weil representation for the split orthogonal group O$_q(2n,2n)$ over a finite field of $q$ elements. Besides, we give an initial decomposition of the representation found. We also show that the constructed representation is equal to the restriction of the Weil representation to O$_q(2n,2n)$ for the reductive dual pair $({\rm Sp}_2(\F_q),{\rm O}_q(2n,2n))$ and that the initial decomposition is the same as the decomposition with respect to the action of Sp$_2(\F_q)$.