  In an interesting work M.F. Muller-Bahns and N. Neumaier ("Some remarks on
g-invariant Fedosov star products and quantum momentum mappings". Journal of
Geometry and Physics 50 (2004), 257-272.) analyze the existence of a quantum
momentum map based on the existence of a classical momentum map providing an
answer to the proposal given by P. Xu in ("Fedosov *-products and quantum
momentum maps". Commun. Math. Phys (1998) 167-197). In both papers only
equivariant classical momentum maps are considered.
  In these notes, we extend Muller-Bahns and Neumaier analysis to the case of a
non equivariant momentum map. In addition, we propose the notion of an
anomalous quantum momentum map as an alternative to recover a non equivariant
momentum map at the classical level by considering central extensions of the
Lie algebra associated with non equivariance.
