Poincaré families and automorphisms of principal bundles on a curve

Abstract

Let C be a smooth projective curve, and let G be a reductive algebraic group. We give a necessary condition, in terms of automorphism groups of principal G-bundles on C, for the existence of Poincaré families parameterized by Zariski-open parts of their coarse moduli schemes. Applications are given for the moduli spaces of orthogonal and symplectic bundles. To cite this article: I. Biswas, N. Hoffmann, C. R. Acad. Sci. Paris, Ser. I 347 (2009).