Addendum: Behavior of a bipartite system in a cavity

This note is an Addendum to our previous article [Phys. Rev. A \textbf{81}, 053820 (2010)]. We show that under the assumption of a Bose-Einstein distribution for the thermal reservoir, zero-temperature properties of the entangled states considered there are not changed by heating, for temperatures up to the order of room temperatures. In this case, the system is dissipative in free space and presents stability for a small cavity, both for T=0 and for finite temperature.Comment: Revtex, 04 pages no figures, Version as accepted for publication in Phys. Rev.

Magnetic effects on spontaneous symmetry breaking/restoration in a toroidal topology

We study temperature and finite-size effects on the spontaneous symmetry breaking/restoration for a scalar field model under the influence of an external magnetic field, at finite chemical potential. We use the 2PI formalism and consider the large-$N$ limit. We find that there is a minimal size of the system to sustain the broken phase, which diminishes as the applied field increases but is independent of the chemical potential. We analyze the critical curves and show that the magnetic field enhances the broken-phase regions, while increasing the chemical potential leads to a diminishement of the critical temperature.Comment: Five pages, five figures, version as accepted for publication in Phys. Rev.

A note on the infrared behavior of the compactified Ginzburg--Landau model in a magnetic field

We consider the Euclidean large-$N$ Ginzburg--Landau model in $D$ dimensions, $d$ ($d\leq D$) of them being compactified. For D=3, the system can be supposed to describe, in the cases of d=1, d=2, and d=3, respectively, a superconducting material in the form of a film, of an infinitely long wire having a rectangular cross-section and of a brick-shaped grain. We investigate the fixed-point structure of the model, in the presence of an external magnetic field. An infrared-stable fixed points is found, which is independent of the number of compactified dimensions. This generalizes previous work for type-II superconducting filmsComment: LATEX, 6 pages no figures. arXiv admin note: 80% of text overlaps with arXiv:1102.139

Palha de trigo para artesanato.

bitstream/CNPT-2010/40544/1/p-co179.pd