  We consider a model of $N$ two-dimensional bosons in a harmonic potential
with weak repulsive delta-function interactions. We show analytically that, for
angular momentum $L\le N$, the elementary symmetric polynomials of particle
coordinates measured from the center of mass are exact eigenstates with energy
$N(N-L/2-1)$. Extensive numerical analysis confirms that these are actually the
ground states, but we are currently unable to prove this analytically. The
special case $L=N$ can be thought of as the generalisation of the usual
superfluid one-vortex state to Bose-Einstein condensates in a trap.
