Infinitesimal cohomology and the Chern character to negative cyclic homology

Abstract

There is a Chern character from K-theory to negative cyclic homology. We show that it preserves the decomposition coming from Adams operations, at least in characteristic 0. This is done by using infinitesimal cohomology to reduce to the case of a nilpotent ideal (which had been established by Cathelineau some time ago).

Included reference for identification of relative Chern and rational homotopy theory characters; some minor editing for clarity