12 research outputs found
Effective Potential for Scalar Field in Three Dimensions: Ising Model in the Ferromagnetic Phase
We compute the effective potential for one-component real
scalar field in three Euclidean dimensions (3D) in the case of
spontaneously broken symmetry, from the Monte Carlo simulation of the 3D Ising
model in external field at temperatures approaching the phase transition from
below. We study probability distributions of the order parameter on the
lattices from to , at . We find that, in close
analogy with the symmetric case, plays an important role: is very well approximated by the sum of , and
terms. An unexpected feature is the negative sign of the
term. As close to the continuum limit as we can get (), we
obtain
We also compute several universal coupling constants and ratios, including
the combination of critical amplitudes .Comment: 13 pages, 5 Postscript figures, uses epsf.st
Suppression of Superfluidity of He in a Nanoporous Glass by Preplating a Kr Layer
Helium in nanoporous media has attracted much interest as a model Bose system
with disorder and confinement. Here we have examined how a change in porous
structure by preplating a monolayer of krypton affects the superfluid
properties of He adsorbed or confined in a nanoporous Gelsil glass, which
has a three-dimensional interconnected network of nanopores of 5.8 nm in
diameter. Isotherms of adsorption and desorption of nitrogen show that
monolayer preplating of Kr decreases the effective pore diameter to 4.7 nm and
broadens the pore size distribution by about eight times from the sharp
distribution of the bare Gelsil sample. The superfluid properties were studied
by a torsional oscillator for adsorbed film states and pressurized liquid
states, both before and after the monolayer Kr preplating. In the film states,
both the superfluid transition temperature and the superfluid
density decrease about 10 percent by Kr preplating. The suppression of film
superfluidity is attributed to the quantum localization of He atoms by the
randomness in the substrate potential, which is caused by the
preplating--induced broadening of the pore size distribution. In the
pressurized liquid states, the superfluid density is found
to increase by 10 percent by Kr preplating, whereas is
decreased by 2 percent at all pressures. The unexpected enhancement of
might indicate the existence of an unknown disorder effect
for confined He.Comment: 27 pages, 8 figures, submitted to J. Phys. Soc. Jp