1,882 research outputs found
Massless Three Dimensional Quantum Electrodynamics and Thirring Model Constrained by Large Flavor Number
We explicitly prove that in three dimensional massless quantum
electrodynamics at finite temperature, zero density and large number of flavors
the number of infrared degrees of freedom is never larger than the
corresponding number of ultraviolet. Such a result, strongly dependent on the
asymptotic freedom of the theory, is reversed in three dimensional Thirring
model due to the positive derivative of its running coupling constant
A comparative evaluation of anomaloscopes: Pickford-Nicholson & Nagel
Included among color vision testing instruments are the Nagel anomaloscope and the Pickford-Nicholson anomaloscope. The Nagel is a spectral instrument whereas the Pickford-Nicholson uses filters. This paper examines how closely the two instruments actually correspond. It is concluded that both instruments do quantitatively yield similar results on both normals and color deficients. The standard deviations of both the means and ranges on the two instruments are equal, at the .02 level of significance
Can Sigma Models Describe Finite Temperature Chiral Transitions?
Large-N expansions and computer simulations indicate that the universality
class of the finite temperature chiral symmetry restoration transition in the
3D Gross-Neveu model is mean field theory. This is a counterexample to the
standard 'sigma model' scenario which predicts the 2D Ising model universality
class. We trace the breakdown of the standard scenario (dimensional reduction
and universality) to the absence of canonical scalar fields in the model. We
point out that our results could be generic for theories with dynamical
symmetry breaking, such as Quantum Chromodynamics.Comment: 9 pages, 2 ps figure
Interpretations of Presburger Arithmetic in Itself
Presburger arithmetic PrA is the true theory of natural numbers with
addition. We study interpretations of PrA in itself. We prove that all
one-dimensional self-interpretations are definably isomorphic to the identity
self-interpretation. In order to prove the results we show that all linear
orders that are interpretable in (N,+) are scattered orders with the finite
Hausdorff rank and that the ranks are bounded in terms of the dimension of the
respective interpretations. From our result about self-interpretations of PrA
it follows that PrA isn't one-dimensionally interpretable in any of its finite
subtheories. We note that the latter was conjectured by A. Visser.Comment: Published in proceedings of LFCS 201
Nature of 45 degree vortex lattice reorientation in tetragonal superconductors
The transformation of the vortex lattice in a tetragonal superconductor which
consists of its 45 degree reorientation relative to the crystal axes is studied
using the nonlocal London model. It is shown that the reorientation occurs as
two successive second order (continuous) phase transitions. The transition
magnetic fields are calculated for a range of parameters relevant for
borocarbide superconductors in which the reorientation has been observed
Equation of state for the 2+1 dimensional Gross-Neveu model at order 1/N
We calculate the equation of state of the Gross-Neveu model in 2+1 dimensions
at order 1/N, where N is the number of fermion species. We make use of a
general formula valid for four-fermion theories, previously applied to the
model in 1+1 dimensions. We consider both the discrete and continuous symmetry
versions of the model. We show that the pion-like excitations give the dominant
contribution at low temperatures. The range of validity for such pion dominance
is analyzed. The complete analysis from low to high temperatures also shows
that in the critical region the role of composite states is relevant, even for
quite large N, and that the free-component behaviour at high T starts at about
twice the mean field critical temperature.Comment: 19 pages, RevTeX, 10 figures.p
Vortex solutions of a Maxwell-Chern-Simons field coupled to four-fermion theory
We find the static vortex solutions of the model of Maxwell-Chern-Simons
gauge field coupled to a (2+1)-dimensional four-fermion theory. Especially, we
introduce two matter currents coupled to the gauge field minimally: the
electromagnetic current and a topological current associated with the
electromagnetic current. Unlike other Chern-Simons solitons the N-soliton
solution of this theory has binding energy and the stability of the solutions
is maintained by the charge conservation laws.Comment: 7 pages, harvmac, To be published in Phys. Rev. D5
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