Equivariant gerbes and momentum maps -- Ping Xu, April 18, 2003

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Using groupoid S^1-central extensions, we present,
for a compact simple  Lie group G,
 an infinite dimensional model of an S^1-gerbe
over the differential stack G/G whose Dixmier-Douady
class corresponds to the canonical generator of the equivariant
 cohomology H_G^3 (G). Applications to momentum map theories
are discussed. In particular, this yields a pre-quantization
of q-Hamiltonian spaces in the sense of Alekseev-Malkin-Meinrenken.