  {}From the one-loop effective potential for a gas of non-relativistic bosons
in two spatial dimensions interacting via a delta-function potential at
zero-temperature and finite chemical potential, the anomaly of the
energy-momentum tensor follows directly. It is also similarly derived when the
bosons have an additional Chern-Simons interaction. In the special case of
anyons, the scale anomaly vanishes to one-loop order in the effective potential
and also to second order in the statistical angle.
