Maximal isotropic subbundles of orthogonal bundles of odd rank over a curve

Abstract

An orthogonal bundle over a curve has an isotropic Segre invariant determined by the maximal degree of a maximal isotropic subbundle. This in- variant and the induced strati cations on moduli spaces of orthogonal bundles were studied for bundles of even rank in [4]. In this paper, we obtain analogous results for bundles of odd rank. We compute the sharp upper bound on the isotropic Segre invariant. Also we show the irreducibility of the induced strata on the moduli spaces of orthogonal bundles of odd rank, and compute their dimensions.