MSC: 53D50 57T10Keywords: Quantization Moduli space of flat connections Riemann surface Lie group a b s t r a c t For a simply connected, compact, simple Lie group G, the moduli space of flat G-bundles over a closed surface Σ is known to be pre-quantizable at integer levels. For non-simply connected G, however, integrality of the level is not sufficient for pre-quantization, and this paper determines the obstruction -namely a certain cohomology class in H 3 (G 2 ; Z)-that places further restrictions on the underlying level. The levels that admit a prequantization of the moduli space are determined explicitly for all non-simply connected, compact, simple Lie groups G.

This paper exhibits equivalences of 2-stacks between certain models of S 1gerbes and differential 3-cocycles. We focus primarily on the model of Dixmier-Douady bundles, and provide an equivalence between the 2-stack of Dixmier-Douady bundles and the 2-stack of differential 3-cocycles of height 1, where the 'height' is related to the presence of connective structure. Differential 3-cocycles of height 2 (resp. height 3) are shown to be equivalent to S 1 -bundle gerbes with connection (resp. with connection and curving). These equivalences extend to the equivariant setting of S 1 -gerbes over Lie groupoids.

This paper computes the quantization of the moduli space of flat SO(3)-bundles over an oriented surface with boundary, with prescribed holonomies around the boundary circles. The result agrees with the generalized Verlinde formula conjectured by Fuchs and Schweigert.

The purpose of this note is to define sheaves for diffeological spaces and give a construction of their Čech cohomology. As an application, we prove that the first degree Čech cohomology classes for the sheaf of smooth functions to an abelian diffeological group G classify diffeological principal G-bundles.

This paper computes the obstruction to the existence of equivariant extensions of basic gerbes over non-simply connected compact simple Lie groups. By modifying a (finite dimensional) construction of Gawȩdzki-Reis [J. Geom. Phys. 50(1):28-55, 2004], we exhibit basic equivariant bundle gerbes over non-simply connected compact simple Lie groups.