Quasi-connected reductive groups

Abstract

We introduce the notion of a quasi-connected reductive group over an arbitrary field to be an almost direct product of a connected semisimple group and a quasi-torus (a smooth group of multiplicative type). We show that a linear algebraic group is quasi-connected reductive if and only if it is isomorphic to a smooth normal subgroup of a connected reductive group.

Withdrawn because it is superseded by the version 2 of arXiv:2103.04654 [math.RT] by the same authors