Eigenvalues of thick regular near hexagons

In this paper, we study a distance-regular graph \(\Gamma \) $\mathrm{\Gamma }$ having a nonintegral eigenvalue \(\theta \) $\theta$ and give some restriction for the intersection numbers. As an application, we show that (the collinearity graph of) a thick regular near hexagon has a nonintegral eigenvalue if and only if it is a generalized hexagon of order (s, 1) such that s is not a square.