Mapping between the Sinh-Gordon and Ising Models

The $S$-matrix of the Ising Model can be obtained as particular limit of the roaming trajectories associated to of the $S$-matrix of the Sinh-Gordon model. Using the form factors of the Sinh-Gordon, we analyse the correspondence between the operators of the two theories.Comment: 10 pages, LATEX file, (two figures not included in the text, to be requested separately) IC/93/143, ISAS/EP/93/8

Non-Subelliptic estimates for the tangential Cauchy-Riemann system

We prove non-subelliptic estimates for the tangential Cauchy-Riemann system over a weakly "$q$-pseudoconvex" higher codimensional submanifold $M$ of \C^n. Let us point out that our hypotheses do not suffice to guarantee subelliptic estimates, in general. Even more: hypoellipticity of the tangential C-R system is not in question (as shows the example by Kohn in case of a Levi-flat hypersurface). However our estimates suffice for existence of smooth solutions to the inhomogeneous C-R equations in certain degree. The main ingredients in our proofs are the weighted $L^2$ estimates by H\"ormander and Kohn and the tangential $\bar\partial$-Neumann operator by Kohn. As for the notion of $q$ pseudoconvexity we follow closely Zampieri. The main technical result is a version for "perturbed" $q$-pseudoconvex domains of a similar result by Ahn who generalizes in turn Chen-Shaw.Comment: 21 page

Magnetoresistivity Modulated Response in Bichromatic Microwave Irradiated Two Dimensional Electron Systems

We analyze the effect of bichromatic microwave irradiation on the magnetoresistivity of a two dimensional electron system. We follow the model of microwave driven Larmor orbits in a regime where two different microwave lights with different frequencies are illuminating the sample ($w_{1}$ and $w_{2}$). Our calculated results demonstrate that now the electronic orbit centers are driven by the superposition of two harmonic oscillatory movements with the frequencies of the microwave sources. As a result the magnetoresisitivity response presents modulated pulses in the amplitude with a frequency of $\frac{w_{1}-w_{2}}{2}$, whereas the main response oscillates with $\frac{w_{1}+w_{2}}{2}$.Comment: 4 pages, 3 figures Accepted in Applied Physics Letter

From zero resistance states to absolute negative conductivity in microwave irradiated 2D electron systems

Recent experimental results regarding a 2D electron gas subjected to microwave radiation reveal that magnetoresistivity, apart from presenting oscillations and zero resistance states, can evolve to negative values at minima. In other words, the current can evolve from flowing with no dissipation, to flow in the opposite direction of the dc bias applied. Here we present a theoretical model in which the existence of radiation-induced absolute negative conductivity is analyzed. Our model explains the transition from zero resistance states to absolute negative conductivity in terms of multiphoton assisted electron scattering due to charged impurities. It shows as well, how this transition can be driven by tuning microwave frequency and intensity. Then it opens the possibility of controlling the electron Larmor orbits dynamics (magnetoconductivity) in microwave driven nanodevices. The analysis of zero resistance states is therefore promising because new optical and transport properties in nanodevices will be expected.Comment: 5 pages and 4 figure

Meta-Stable Brane Configurations by Adding an Orientifold-Plane to Giveon-Kutasov

In hep-th/0703135, they have found the type IIA intersecting brane configuration where there exist three NS5-branes, D4-branes and anti-D4-branes. By analyzing the gravitational interaction for the D4-branes in the background of the NS5-branes, the phase structures in different regions of the parameter space were studied in the context of classical string theory. In this paper, by adding the orientifold 4-plane and 6-plane to the above brane configuration, we describe the intersecting brane configurations of type IIA string theory corresponding to the meta-stable nonsupersymmetric vacua of these gauge theories.Comment: 21 pp, 6 figures; reduced bytes of figures, DBI action analysis added and to appear in JHE

Elementary Excitations in One-Dimensional Electromechanical Systems; Transport with Back-Reaction

Using an exactly solvable model, we study low-energy properties of a one-dimensional spinless electron fluid contained in a quantum-mechanically moving wire located in a static magnetic field. The phonon and electric current are coupled via Lorentz force and the eigenmodes are described by two independent boson fluids. At low energies, the two boson modes are charged while one of them has excitation gap due to back-reaction of the Lorentz force. The theory is illustrated by evaluating optical absorption spectra. Our results are exact and show a non-perturbative regime of electron transport

Direct correlation functions of the Widom-Rowlinson model

We calculate, through Monte Carlo numerical simulations, the partial total and direct correlation functions of the three dimensional symmetric Widom-Rowlinson mixture. We find that the differences between the partial direct correlation functions from simulation and from the Percus-Yevick approximation (calculated analytically by Ahn and Lebowitz) are well fitted by Gaussians. We provide an analytical expression for the fit parameters as function of the density. We also present Monte Carlo simulation data for the direct correlation functions of a couple of non additive hard sphere systems to discuss the modification induced by finite like diameters.Comment: 16 pages, 7 figure

Approximating the Maximum Overlap of Polygons under Translation

Let $P$ and $Q$ be two simple polygons in the plane of total complexity $n$, each of which can be decomposed into at most $k$ convex parts. We present an $(1-\varepsilon)$-approximation algorithm, for finding the translation of $Q$, which maximizes its area of overlap with $P$. Our algorithm runs in $O(c n)$ time, where $c$ is a constant that depends only on $k$ and $\varepsilon$. This suggest that for polygons that are "close" to being convex, the problem can be solved (approximately), in near linear time

Supersymmetry Breaking Vacua from M Theory Fivebranes

We consider intersecting brane configurations realizing N=2 supersymmetric gauge theories broken to N=1 by multitrace superpotentials, and softly to N=0. We analyze, in the framework of M5-brane wrapping a curve, the supersymmetric vacua and the analogs of spontaneous supersymmetry breaking and soft supersymmetry breaking in gauge theories. We show that the M5-brane does not exhibit the analog of metastable spontaneous supersymmetry breaking, and does not have non-holomorphic minimal volume curves with holomorphic boundary conditions. However, we find that any point in the N=2 moduli space can be rotated to a non-holomorphic minimal volume curve, whose boundary conditions break supersymmetry. We interpret these as the analogs of soft supersymmetry breaking vacua in the gauge theory.Comment: 32 pages, 8 figures, harvmac; v2: corrections in eq. 3.6 and in section 6, reference adde

Finite size effects in quantum field theories with boundary from scattering data

We derive a relation between leading finite size corrections for a 1+1 dimensional quantum field theory on a strip and scattering data, which is very similar in spirit to the approach pioneered by Luscher for periodic boundary conditions. The consistency of the results is tested both analytically and numerically using thermodynamic Bethe Ansatz, Destri-de Vega nonlinear integral equation and classical field theory techniques. We present strong evidence that the relation between the boundary state and the reflection factor one-particle couplings, noticed earlier by Dorey et al. in the case of the Lee-Yang model extends to any boundary quantum field theory in 1+1 dimensions.Comment: 24 pages, 1 eps figure. Clarifying comments and a reference adde