1,311 research outputs found
A New Field Theoretic Approach to Criticality
A reorganized perturbation expansion with a propagator of soft infrared
behavior is used to study the critical behavior of the mass gap. The condition
of relativistic covariance fixes the form of the soft propagator. Finite
approximants to the correlation critical exponent can be obtained in every
order of the modified, soft perturbation expansion. Alternatively, a convergent
series of exponents in large orders of the soft perturbation expansion is
provided by the renormalization group in all spatial dimensions, . The result of the -expansion is recovered in the
limit.Comment: 22 page
Gauge theories induced by bosons in fundamental representation
A lattice theory of scalar bosons in the fundamental representation of the
gauge group and of the global symmetry group is shown to
induce a standard gauge theory only at large . The system is in a
deconfined phase at strong scalar self-coupling and any finite . The
requirement of convergence of the effective gauge action imposes a lower limit
on the scalar mass.Comment: 11 page
Lattice field theories with an energy current
We investigate a lattice scalar field theory in the presence of a bias
favouring the establishment of an energy current, as a model for stationary
nonequilibrium processes at low temperature in a non-integrable system. There
is a transition at a finite value of the bias to a gapless modulated phase
which carries a classical current; however, unlike in similar, integrable,
models, quantum effects also allow for a non-zero current at arbitrarily small
bias. The transition is second order in the magnetically disordered phase, but
is pre-empted by a first-order transition in the ferromagnetic case, at least
at the mean-field level.Comment: 19 pages, LaTeX, 3 postscript figure
A study of the XY model by the Monte Carlo method
The massively parallel processor is used to perform Monte Carlo simulations for the two dimensional XY model on lattices of sizes up to 128 x 128. A parallel random number generator was constructed, finite size effects were studied, and run times were compared with those on a CRAY X-MP supercomputer
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