Projective structures and Hodge theory

Abstract

Every compact Riemann surface $X$ admits a natural projective structure $p_u$ as a consequence of the uniformization theorem. In this work we describe the construction of another natural projective structure on $X$, namely the Hodge projective structure $p_h$, related to the second fundamental form of the period map. We then describe how projective structures correspond to $(1,1)$-differential forms on the moduli space of projective curves and, from this correspondence, we deduce that $p_u$ and $p_h$ are not the same structure.

This paper is based on the plenary conference "Strutture proiettive e teoria di Hodge" given by the second author at the XXII Congress of the "Unione Matematica Italiana", held in Pisa in September 5, 2023