Jordan blocks of unipotent elements in some irreducible representations of classical groups in good characteristic

Abstract

Let $G$ be a classical group with natural module $V$ over an algebraically closed field of good characteristic. For every unipotent element $u$ of $G$, we describe the Jordan block sizes of $u$ on the irreducible $G$-modules which occur as composition factors of $V\otimes V^{\ast }$, ${\wedge }^2(V)$, and $S^2(V)$. Our description is given in terms of the Jordan block sizes of the tensor square, exterior square, and the symmetric square of $u$, for which recursive formulae are known.

to appear in Proc. Amer. Math. Soc