Avalanche in the Valley (Fermions, Anomaly and Unitarity in High-Energy Electroweak Interactions)

Problems related to fermions, unitarity and chiral anomaly in high energy electroweak interactions, are investigated. Particular attention is paid to the correct functional integration over fermion fields in the background of instanton-anti\-instanton type configurations. This leads to an expansion of correlation functions in terms of a small parameter, $\rho/R$, when the instanton-antiinstanton separation ($R$) is large compared to their sizes ($\rho$). Applying such a method to widely discussed cases of fermion-number violation in the electroweak theory, we conclude that there are no theoretical basis for expecting anomalous cross sections to become observable at energies in the $10$ TeV region.Comment: 11 pages + 1 figure (not included

Fermions in Instanton Anti-Instanton Background

We consider the behaviour of fermions in the background of instanton-anti\-instanton type configurations. Several different physics problems, from the high energy electroweak interactions to the study of vacuum structure of QCD and of large orders of perturbation theory are related to this problem. The spectrum of the Dirac operator in such a background is studied in detail. We present an approximation for the fermion correlation function when the instanton-anti\-instanton separation ($R$) is large compared to their sizes ($\rho$). The situation when the instanton-anti\-instanton overlap and melt, is studied through the behaviour of the Chern Simons number as a function of $R/\rho$ and $x_4$. Applying our results to widely discussed cases of fermion-number violation in the electroweak theory, we conclude that there are no theoretical basis for expecting anomalous cross sections to become observable at energies in $10$ TeV region.Comment: 36 PAGES, GEF-Th-8/199

Antidumping and safeguard mechanisms : the Brazilian experience, 1988-2003

The authors focus on the evaluation of the antidumping regime from 1988 through 2003. During these years the Brazilian economy had to cope with several periods of macroeconomic instability and overvaluation of the domestic currency, particularly from 1990-92 and 1994-98. As a result, from 1992 through 1998, import volumes increased significantly. Although during these years, the demand for antidumping protection was growing, the number of investigations concluded with an affirmative determination was only 52 percent. The authors explain that the institutional framework in charge of administering the antidumping regime was subject to several reforms. Along this process, the Ministry of Development, Industry, and Trade saw its role strengthened. This ministry has a more protectionist bias than the Ministry of Finance that, during the initial years of the liberalization program, played a prominent role in decisions regarding antidumping investigations and measures. The authors conclude that in comparison with other countries that are important users of the antidumping mechanism, the Brazilian experience reveals two interesting features: 1) A relatively small rate of final positive determinations. 2) A tradition of applying antidumping duties in amounts that on average have been quite lower than the full dumping margins.TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Economic Theory&Research,Environmental Economics&Policies,Trade Policy,Rules of Origin

Improved Convergence Proof of the Delta Expansion and Order Dependent Mappings

We improve and generalize in several accounts the recent rigorous proof of convergence of delta expansion - order dependent mappings (variational perturbation expansion) for the energy eigenvalues of anharmonic oscillator. For the single-well anharmonic oscillator the uniformity of convergence in $g\in[0,\infty]$ is proven. The convergence proof is extended also to complex values of $g$ lying on a wide domain of the Riemann surface of $E(g)$. Via the scaling relation \`a la Symanzik, this proves the convergence of delta expansion for the double well in the strong coupling regime (where the standard perturbation series is non Borel summable), as well as for the complex ``energy eigenvalues'' in certain metastable potentials. Sufficient conditions for the convergence of delta expansion are summarized in the form of three theorems, which should apply to a wide class of quantum mechanical and higher dimensional field theoretic systems.Comment: some bugs of uuencoded postscript figures are fixe

Noise and diffusion of particles obeying asymmetric exclusion processes

The relation between noise and Fick's diffusion coefficient in barrier limited transport associated with hopping or tunneling mechanisms of particles obeying the asymmetric simple exclusion processes (ASEP) is physically assessed by Monte Carlo simulations. For a closed ring consisting of a large number of barriers the diffusion coefficient is related explicitly to the current noise thus revealing the existence of a generalized Nyquist-Einstein relation. Both diffusion and noise are confirmed to decrease as the square root of the number of barriers as a consequence of the correlation induced by ASEP. By contrast, for an open linear chain of barriers the diffusion coefficient is found to be no longer related to current noise. Here diffusion depends on particle concentration but is independent of the number of barriers