Parabolic vector bundles on Klein surfaces

Abstract: Given a discrete subgroup $\Gamma$ of finite co-volume of $\mathrm{PGL}(2,\mathbb{R})$, we define and study parabolic vector bundles on the quotient $\Sigma$ of the (extended) hyperbolic plane by $\Gamma$. If $\Gamma$ contains an orientation-reversing isometry, then the above is equivalent to studying real and quaternionic parabolic vector bundles on the orientation cover of $\Sigma$. We then prove that isomorphism classes of polystable real and quaternionic parabolic vector bundles are in bijective correspondence with equivalence classes of real and quaternionic unitary representations of $\Gamma$. Similar results are obtained for compact-type real parabolic vector bundles over Klein surfaces.