Exceptional scatteredness in prime degree

Abstract

Let $q$ be an odd prime power and $n$ be a positive integer. Let $\ell \in {\mathbb{F}}_{q^n}[x]$ be a $q$-linearised $t$-scattered polynomial of linearized degree $r$. Let $d=\max \{t,r\}$ be an odd prime number. In this paper we show that under these assumptions it follows that $\ell =x$. Our technique involves a Galois theoretical characterization of $t$-scattered polynomials combined with the classification of transitive subgroups of the general linear group over the finite field ${\mathbb{F}}_q$.