On the theory of vortex quantum tunnelling in the dense Bose superfluid helium II

The quantum tunnelling and nucleation theory of vortices in helium II is re viewed. Arguments are given that the only reliable method to calculate tunn elling probabilities in this highly correlated, strongly interacting many-b ody system is the semiclassical, large-scale approach for evaluation of the tunnelling exponent, which does not make any assumptions about the unknown dynamical behaviour of the fluid on microscopic scales. The geometric impl ications of this semiclassical theory are represented in some detail and it s relevance for the interpretation of experimental data is discussed. (C) 1 998 Elsevier Science B.V. All rights reserved.