Zeros of replicable functions

Abstract

Following the work of Asai, Kaneko, and Ninomiya for Faber polynomials associated to $\mathrm{PSL}_2(\mathbb{Z})$, and Bannai, Kojima, and Miezaki's partial proof for the case of $\Gamma_0^*(2)$, we show that the zeros of certain modular functions associated to some low-level genus zero groups are all located on the boundary of certain natural fundamental domains for $\Gamma$. The groups considered are $\Gamma_0^*(2)$, $\Gamma_0^*(3)$, $\Gamma_0(2\Vert 2)$, $\Gamma_0^*(5)$, $\Gamma_0(6)+$, $\Gamma_0^*(7)$, $\Gamma_0(4\Vert 2)+$, $\Gamma_0(3\Vert 3)$, and $\Gamma_0(10)+$.