Let $\mathbf{ G}$ be a connected reductive group over a finite field $\mathbb{ F}_q$ of characteristic $p > 0$. In this paper, we study a category which we call Deligne--Lusztig category $\mathcal{ O}$ and whose definition is similar to category $\mathcal{ O}$. We use this to construct a collection of representations of $\mathbf{ G}(\mathbb{ F}_q)$ which we call the tilting representations. They form a generating collection of integral projective representations of $\mathbf{ G}(\mathbb{ F}_q)$. Finally we compute the character of these representations and relate their expression to previous calculations of Lusztig and we then use this to establish a conjecture of Dudas--Malle.
Categories: math.RT