Drinfeld centers for bicategories

We generalize Drinfeld’s notion of the center of a tensor category to bicategories. In this generality, we present a spectral sequence to compute the basic invariants of Drinfeld centers: the abelian monoid of isomorphism classes of objects, and the abelian automorphism group of its identity object. There is an associated obstruc-tion theory that explains the difference between the Drinfeld center and the cente