Langevin Simulation of the Chirally Decomposed Sine-Gordon Model

A large class of quantum and statistical field theoretical models, encompassing relevant condensed matter and non-abelian gauge systems, are defined in terms of complex actions. As the ordinary Monte-Carlo methods are useless in dealing with these models, alternative computational strategies have been proposed along the years. The Langevin technique, in particular, is known to be frequently plagued with difficulties such as strong numerical instabilities or subtle ergodic behavior. Regarding the chirally decomposed version of the sine-Gordon model as a prototypical case for the failure of the Langevin approach, we devise a truncation prescription in the stochastic differential equations which yields numerical stability and is assumed not to spoil the Berezinskii-Kosterlitz-Thouless transition. This conjecture is supported by a finite size scaling analysis, whereby a massive phase ending at a line of critical points is clearly observed for the truncated stochastic model.Comment: 6 pages, 4 figure

The SO(N) principal chiral field on a half-line

We investigate the integrability of the SO(N) principal chiral model on a half-line, and find that mixed Dirichlet/Neumann boundary conditions (as well as pure Dirichlet or Neumann) lead to infinitely many conserved charges classically in involution. We use an anomaly-counting method to show that at least one non-trivial example survives quantization, compare our results with the proposed reflection matrices, and, based on these, make some preliminary remarks about expected boundary bound-states.Comment: 7 pages, Late

Supersymmetric WZW σ\sigma Model on Full and Half Plane

We study classical integrability of the supersymmetric U(N) $\sigma$ model with the Wess-Zumino-Witten term on full and half plane. We demonstrate the existence of nonlocal conserved currents of the model and derive general recursion relations for the infinite number of the corresponding charges in a superfield framework. The explicit form of the first few supersymmetric charges are constructed. We show that the considered model is integrable on full plane as a concequence of the conservation of the supersymmetric charges. Also, we study the model on half plane with free boundary, and examine the conservation of the supersymmetric charges on half plane and find that they are conserved as a result of the equations of motion and the free boundary condition. As a result, the model on half plane with free boundary is integrable. Finally, we conclude the paper and some features and comments are presented.Comment: 12 pages. submitted to IJMP

Phase Space Reduction and the Instanton Crossover in (1+1)-Dimensional Turbulence

We study (1+1)-dimensional turbulence in the framework of the Martin-Siggia-Rose field theory formalism. The analysis is focused on the asymptotic behaviour at the right tail of the probability distribution function (pdf) of velocity differences, where shock waves do not contribute. A BRS-preserving scheme of phase space reduction, based on the smoothness of the relevant velocity fields, leads to an effective theory for a few degrees of freedom. The sum over fluctuations around the instanton solution is written as the expectation value of a functional of the time-dependent physical fields, which evolve according to a set of Langevin equations. A natural regularization of the fluctuation determinant is provided from the fact that the instanton dominates the action for a finite time interval. The transition from the turbulent to the instanton dominated regime is related to logarithmic corrections to the saddle-point action, manifested on their turn as multiplicative power law corrections to the velocity differences pdf.Comment: The revised version contains more detailed discussions on some technical point

Wheat lines, suffering structural rearrangements between wheat-1BS and rye-1RS chromosomes, display differential patterns of magnesium accumulation

Poster no. 238Two near isogenic lines, designated as 1RS and 1RW, resulting from the recombination of the rye (Secale cereale) chromosome 1RS with chromosome 1BS of bread wheat (Triticum aestivum), differ in a relatively small region of that short chromosome arm. We have recently reported that chromosome rearrangements in this region imply modifications in the dosage of some genes (including OPRIII codifying an enzyme involved in jasmonic acid (JA) biosynthesis pathway). This dosage difference confer differential drought resistance in a way primarily associated to the capacity of roots for soil exploration. An emerging question is whether or not those rearrangements also differentially influence plant mineral nutrition. In the present study we analyzed the ionome of 1RS and 1RW, which unveiled the existence of relevant differences in the distribution of magnesium (Mg) between the shoot and the root of these lines. Following this observation, we explored the physiological and molecular determinants of differential magnesium accumulation observed.Instituto de Recursos BiológicosFil: Gualano, L.D. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Tecnológico Chascomús; Argentina. Universidad Nacional de San Martín; ArgentinaFil: Moriconi, Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Tecnológico Chascomús; Argentina. Universidad Nacional de San Martín; ArgentinaFil: Tranquilli, Gabriela. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: Santa-María, Guillermo E. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Tecnológico Chascomús; Argentina. Universidad Nacional de San Martín; Argentin

Physiological and genetic characterization of wheat lines sharply differing in sodium accumulation

Poster no. 129Improving nutrient use efficiency is an important objective in modern breeding programs. Our group attempts to elucidate the components that contribute to greater efficiencies of potassium (K) acquisition and utilization in wheat (Triticum aestivum), and its nexus with sodium (Na) dynamics.Instituto de Recursos BiológicosFil: Silva, Martha M. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: Moriconi, Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Tecnológico Chascomús; Argentina. Universidad Nacional de San Martín; ArgentinaFil: Gualano, L.D. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Tecnológico Chascomús; Argentina. Universidad Nacional de San Martín; ArgentinaFil: Tranquilli, Gabriela. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: Santa-María, Guillermo E. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Tecnológico Chascomús; Argentina. Universidad Nacional de San Martín; Argentin

Special Theory of Relativity through the Doppler Effect

We present the special theory of relativity taking the Doppler effect as the starting point, and derive several of its main effects, such as time dilation, length contraction, addition of velocities, and the mass-energy relation, and assuming energy and momentum conservation, we discuss how to introduce the 4-momentum in a natural way. We also use the Doppler effect to explain the "twin paradox", and its version on a cylinder. As a by-product we discuss Bell's spaceship paradox, and the Lorentz transformation for arbitrary velocities in one dimension.Comment: 20 pages, 1 figur