Scaling of the speci c heat of super

We investigate the scaling properties of the speciic heat of the XY model on lattices H H L with L H (i.e. in a bar-like geometry) with respect to the thickness H of the bar, using the Cluster Monte Carlo method. We study the eeect of the geometry and boundary conditions on the shape of the universal scaling function of the speciic heat by comparing the scaling functions obtained for cubic, lm, and bar-like geometry. In the presence of physical boundary conditions applied along the sides of the bars we nd good agreement between our Monte Carlo results and the most recent experimental data for superruid helium connned in pores.