Equations for superelliptic curves over their minimal field of definition

Abstract

Let ${\mathcal{X}}_g$ be a genus $g\ge 2$ superelliptic curve, $F$ its field of moduli, and $K$ the minimal field of definition. In this short note we construct an equation of the curve ${\mathcal{X}}_g$ over its minimal field of definition $K$ when ${\mathcal{X}}_g$ has extra automorphisms. We make use of the dihedral invariants of superelliptic curves as defined by Shaska in [6] and results on the automorphism groups of superelliptic curves as in [10].