Automorphisms of moduli spaces of principal bundles over a smooth curve.

For any almost-simple group G over an algebraically closed field k of characteristic zero, we describe the automorphism group of the moduli space of semistable G -bundles over a connected smooth projective curve C of genus at least 4. The result is achieved by studying the singular fibers of the Hitchin fibration. As a byproduct, we provide a description of the irreducible components of two natural closed subsets in the Hitchin basis: the divisor of singular cameral curves and the divisor of singular Hitchin fibers. [ABSTRACT FROM AUTHOR]