Maximal Higgs bundles for adjoint forms via Cayley correspondence

Abstract

For a fixed compact Riemann surface X, of genus at least 2, we count the number of connected components of the moduli space of maximal Higgs bundles over X for the hermitian groups PSp(2n, R), PSO*(2n), PSO0(2, n) and E-6(-14). Hence the same result follows for the number of connected components of the moduli space of maximal representations of pi X-1 in these groups. We use the Cayley correspondence proved in Biquard et al. (Higgs bundles, the Toledo invariant and the Cayley correspondence. Preprint, 2015. arXiv: 1511.07751) as our main tool.