  In this paper we relate a problem in representation theory - the study of
Yetter-Drinfeld modules over certain braided Hopf algebras - to a problem in
two-dimensional quantum field theory, namely the identification of integrable
perturbations of a conformal field theory. A prescription that parallels
Lusztig's construction allows one to read off the quantum group governing the
integrable symmetry. As an example, we illustrate how the quantum group for the
loop algebra of sl(2) appears in the integrable structure of the perturbed
uncompactified and compactified free boson.
