Title:   Chromatic characteristic classes in ordinary group cohomology
Authors: David J. Green <green@math.uni-wuppertal.de>
         John R. Hunton <J.Hunton@mcs.le.ac.uk>
         Bj"orn Schuster <schuster@math.uni-wuppertal.de>
MSC:     20J06 (primary), 16W30 55P47 55R40 (secondary)
arXiv:   math.AT/0109019
Status:  Topology 42 (2003), no. 1, 243-263.

Abstract:
We study a family of subrings, indexed by the natural
numbers, of the mod-p cohomology of a finite group G.
These subrings are based on a family of v_n-periodic
complex oriented cohomology theories and are constructed as
rings of generalised characteristic classes. We identify the
varieties associated to these subrings in terms of colimits
over categories of elementary abelian subgroups of G,
naturally interpolating between the work of Quillen on
var(H^*(BG)), the variety of the whole
cohomology ring, and that of Green and Leary on the variety
of the Chern subring, var(Ch(G)). Our subrings give rise
to a "chromatic" (co)filtration, which has both
topological and algebraic definitions, of var(H^*(BG))
whose final quotient is the variety var(Ch(G)).