Monte Carlo simulations of the two-dimensional XY model are performed in a
square geometry with various boundary conditions (BC). Using conformal mappings
we deduce the exponent ησ(T) of the order parameter correlation
function and its surface analogue η∥(T) as a function of the temperature
in the critical (low-temperature) phase of the model.Comment: 26 pages, iop macro, one reference added, typos correcte