On a complex topological orientation for circle-equivariant K-theory

Abstract

The principal result of this note is the existence of a complex topological orientation for Atiyah-Segal $\mathbb{T}$-equivariant K-theory which indexes the projective space of lines in complex (n+1)-space by the Fourier expansion $1+q+\cdots +q^n$.

better references, some small additions; thanks to S Devalapurkar re Krichever and further