``Cosmological'' scenario for A-B phase transition in superfluid 3He

At a very rapid superfluid transition in $^3$He, follows after a reaction with single neutron, the creation of topological defects (vortices) has recently been demonstrated in accordance with the Kibble-Zurek scenario for the cosmological analogue. We discuss here the extension of the Kibble-Zurek scenario to the case when alternative symmetries may be broken and different states nucleated independently. We have calculated the nucleation probability of the various states of superfluid $^3$He during a superfluid transition. Our results can explain the transition from supercooled $A$ phase to the $B$ phase, triggered by nuclear reaction. The new scenario is an alternative to the well-known ``baked Alaska'' scenario.