On the Fourier coefficients of 2-dimensional vector-valued modular forms

Abstract

Let $\rho :SL(2,\mathbb{Z})\to GL(2,\mathbb{C})$ be an irreducible representation of the modular group such that $\rho (T)$ has finite order $N$. We study holomorphic vector-valued modular forms $F(\tau )$ of integral weight associated to $\rho$ which have \emph{rational} Fourier coefficients. (These span the complex space of all integral weight vector-valued modular forms associated to $\rho$.) As a special case of the main Theorem, we prove that if $N$ does \emph{not} divide 120 then every nonzero $F(\tau )$ has Fourier coefficients with \emph{unbounded denominators}.

References in corpus (1)

• Structure of the module of vector-valued modular forms