This thesis reports numerical calculations on quantized vortices in He and He superfluids. Vortices are of crucial importance in understanding many of the superfluid properties. All the calculations presented in the thesis have experimental relevance, either in understanding measured results or in predicting the outcome of planned experiments. Superfluid He has been observed to exhibit incomple...

The main goal of this work is to investigate the possibility of finding the supersymmetric version of the U(1)-global string model which behaves as a vortex-superfluid. To describe the superfluid phase, we introduce a Lorentz-symmetry breaking background that, in an approach based on supersymmetry, leads to a discussion on the relation between the violation of Lorentz symmetry and explicit soft...

We consider quantum global vortex string correlation functions, within the Kalb-Ramond framework, in the presence of a background field-strength tensor and investigate the conditions under which this yields a nontrivial contribution to those correlation functions. We show that a background field must be supplemented to the Kalb-Ramond theory, in order to correctly describe the quantum propertie...