Weierstrass filtration on Teichmüller curves and Lyapunov exponents: Upper bounds

Abstract

We get an upper bound of the slope of each graded quotient for the Harder-Narasimhan filtration of the Hodge bundle of a Teichmüller curve. As an application, we show that the sum of Lyapunov exponents of a Teichmüller curve does not exceed ${(g+1)}/{2}$, with equality reached if and only if the curve lies in the hyperelliptic locus induced from $\mathcal{Q}(2k_1,...,2k_n,-1^{2g+2})$ or it is a special Teichmüller curve in $Ω\mathcal{M}_g(1^{2g-2})$. It also gives an unified interpretation for many known results about the special partial sums of Lyapunov exponents on Teichmüller curves.

19 page. We rewrite this paper without changing the mathematics content