Growth rates of cocompact hyperbolic Coxeter groups and 2-Salem numbers

By the results of Cannon, Wagreich and Parry, it is known that the growth rate of a cocompact Coxeter group in 2-dimensional hyperbolic space $H^2$ and 3-dimensional hyperbolic space $H^3$ is a Salem number. Kerada defined a j-Salem number, which is a generalization of a Salem number. In this paper, we realize infinitely many 2-Salem numbers as the growth rates of cocompact Coxeter groups in 4-dimensional hyperbolic space $H ^4$. Our Coxeter polytopes are constructed by successive gluing of Coxeter polytopes which we call Coxeter dominoes.