Density of monodromy actions on non-abelian cohomology

Abstract

In this paper we study the monodromy action on the first Betti and de Rham non-abelian cohomology arising from a family of smooth curves. We describe sufficient conditions for the existence of a Zariski dense monodromy orbit. In particular we show that for a Lefschetz pencil of sufficiently high degree the monodromy action is dense.

LaTeX2e, 48 pages, Version substantially revised for publication. A gap in the proof of the density for Lefschetz pencils is fixed. The case of hyperelliptic monodromy is also treated in detail