A note on the phase transition in a topologically massive Ginzburg-Landau theory

We consider the phase transition in a model which consists of a Ginzburg-Landau free energy for superconductors including a Chern-Simons term. The mean field theory of Halperin, Lubensky and Ma [Phys. Rev. Lett. 32, 292 (1974)] is applied for this model. It is found that the topological mass, $\theta$, drives the system into different regimes of phase transition. For instance, there is a $\theta_{c}$ such that for $\theta<\theta_{c}$ a fluctuation induced first order phase transition occurs. On the other hand, for $\theta>\theta_{c}$ only the second order phase transition exists. The 1-loop renormalization group analysis gives further insight to this picture. The fixed point structure exhibits tricritical and second order fixed points.Comment: Revised version; uses a more physical parametrization of the renormalization group equations; new references added; one figure added; EuroLatex, 6 page

A non-perturbative approach to the Coleman- Weinberg mechanism in massless scalar QED

We rederive non-perturbatively the Coleman-Weinberg expression for the effective potential for massless scalar QED. Our result is not restricted to small values of the coupling constants. This shows that the Coleman- Weinberg result can be established beyond the range of validity of perturbation theory. Also, we derive it in a manifestly renormalization group invariant way. It is shown that with the derivation given no Landau ghost singularity arises. The finite temperature case is discussed. Pacs number: 11.10.Ef,11.10.Gh

Dynamic critical behaviour in Ising spin glasses

The critical dynamics of Ising spin glasses with Bimodal, Gaussian, and Laplacian interaction distributions are studied numerically in dimensions 3 and 4. The data demonstrate that in both dimensions the critical dynamic exponent $z_{\rm c}$, the non-equilibrium autocorrelation decay exponent $\lambda_c/z_{\rm c}$, and the critical fluctuation-dissipation ratio $X_{\infty}$ all vary strongly and systematically with the form of the interaction distribution.Comment: 8 pages, 4 figures, version to appear in Phys. Rev.

Planejamento da coleta de sementes florestais nativas.

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