On the rank of the flat unitary summand of the Hodge bundle

Vìctor González-Alonso, Lidia Stoppino, Sara Torelli

Let $f:S\to B$ be a non-isotrivial fibred surface. We prove that the genus $g$, the rank $u_f$ of the unitary summand of the Hodge bundle $f_{\ast }{\omega }_f$ and the Clifford index $c_f…