Seminormal basis for the cyclotomic Hecke algebra of type $G(r,p,n)$

Abstract

The cyclotomic Hecke algebra $H_{r,p,n}$ of type $G(r,p,n)$ (where $r=pd$) can be realized as the $\sigma$-fixed point subalgebra of certain cyclotomic Hecke algebra $H_{r,n}$ of type $G(r,1,n)$ with some special cyclotomic parameters, where $\sigma$ is an automorphism of $H_{r,n}$ of order $p$. In this paper we prove a number of rational properties on the $\gamma$-coefficients arising in the construction of the seminormal basis for the semisimple Hecke algebra $H_{r,n}$. Using these properties, we construct a seminormal basis for the semisimple Hecke algebra $H_{r,p,n}$ in terms of the seminormal basis for the semisimple Hecke algebra $H_{r,n}$. The proof relies on some careful and subtle study on some rational and symmetric properties of some quotients and/or products of $\gamma$-coefficients of $H_{r,n}$. As applications, we obtain an explicit basis for the center $Z(H_{r,p,n})$ and an explicit basis for the $\sigma$-twisted $k$-center $Z(H_{r,n}{)}^{(k)}$ of $H_{r,n}$ for each $k\in \mathbb{Z}/p\mathbb{Z}$.