Heisenberg homology on surface configurations
Résumé
Motivated by the Lawrence-Krammer-Bigelow representations of the classical braid groups, we study the homology of unordered configurations in an orientable genus-$g$ surface with one boundary component, over non-commutative local systems defined from representations of the discrete Heisenberg group. For a general representation of the Heisenberg group we obtain a twisted representation of the mapping class group. For the linearisation of the affine translation action of the Heisenberg group we obtain a genuine, untwisted representation of the mapping class group. In the case of the Schr\"odinger representation or its finite-dimensional analogues, by composing with a Stone-von Neumann isomorphism we obtain a representation to the projective unitary group, which lifts to a unitary representation of the stably universal central extension of the mapping class group.