Horizontal Ga-actions on affine T-varieties of complexity one

Abstract

We classify the ${\mathbb{G}}_a$-actions on normal affine varieties defined over any field that are horizontal with respect to a torus action of complexity one. This generalizes previous results that were available for perfect ground fields (cf. [Flenner-Zaidenberg2005, Liendo2010, L-Liendo2016]).

14 pages. To appear in Le Matematiche