The sigma orientation for analytic circle-equivariant elliptic cohomology
The sigma orientation for analytic circle-equivariant elliptic cohomology
We construct a canonical Thom isomorphism in Grojnowski's equivariant elliptic cohomology, for virtual T-oriented T-equivariant spin bundles with vanishing Borel-equivariant second Chern class, which is natural under pull-back of vector bundles and exponential under Whitney sum.It extends in the complexanalytic case the non-equivariant sigma orientation of Hopkins, Strickland, and the …