Minimal superfluid vortices in chiral perturbation theory

We derive some properties of rotational vortices in the pion condensed phase. Employing leading order chiral perturbation theory we determine the minimal energy condition for vortex nucleation. Vortices have quantized angular momentum along the rotation axis, an hallmark of superfluidity, and self-confine pions. The critical rotation frequency for vortex nucleation is estimated.