AbstractSiegel modular forms generalize the usual elliptic modular forms and show up in many parts of mathematics: algebraic geometry, number theory and even in mathematical physics. But they are difficult to construct. We show that invariant theory enables us to efficiently construct all (vector valued) Siegel modular forms of degree two and three from from certain basic modular forms provided...
Abstract: Non-abelian Hodge theory relates representations of the fundamental group of a compact Riemann surface X into a Lie group G with holomorphic objects on X known as Higgs bundles, introduced by Hitchin more than 35 years ago. Starting with the case in which G is the circle, and the 19th century Abel-Jacobi's theory, we will move to the case of G=SL(2,R) and the relation to Teichmüller t...