The wave functionals for the excited states of the two-dimensional planar rotator model are constructed approximately with the help of analytical ansätze. The mass gap so calculated is found to be in quantitative agreement with theoretical expectations for any T>Tc. The order-disorder type transition line of the generalized model with Ising type symmetry breaking term is obtained using a similar ansatz.
ASJC Scopus subject areas
- Nuclear and High Energy Physics