Brauer character degrees and nilpotent subgroups

Abstract

We solve a question raised by Chen and Navarro concerning Brauer characters and nilpotent subgroups. Let $N\lhd G$, assume that $G/N$ is solvable, and let $N\leq H\leq G$ with $H/N$ nilpotent. We prove that for every irreducible $\ell$-Brauer character $θ$ of $H$ there exists an irreducible $\ell$-Brauer character $χ$ of $G$ such that $θ$ is a constituent of $χ_H$ and $χ(1)$ divides $|G:H|θ(1)$.