Global-String and Vortex Superfluids in a Supersymmetric Scenario

The main goal of this work is to investigate the possibility of finding the supersymmetric version of the U(1)-global string model which behaves as a vortex-superfluid. To describe the superfluid phase, we introduce a Lorentz-symmetry breaking background that, in an approach based on supersymmetry, leads to a discussion on the relation between the violation of Lorentz symmetry and explicit soft supersymmetry breakings. We also study the relation between the string configuration and the vortex-superfluid phase. In the framework we settle down in terms of superspace and superfields, we actually establish a duality between the vortex degrees of freedom and the component fields of the Kalb-Ramond superfield. We make also considerations about the fermionic excitations that may appear in connection with the vortex formation.Comment: 9 pages. This version presented the relation between Lorentz symmetry violation by the background and the appearance of terms that explicitly break SUS

Broadening effects due to alloy scattering in Quantum Cascade Lasers

We report on calculations of broadening effects in QCL due to alloy scattering. The output of numerical calculations of alloy broadened Landau levels compare favorably with calculations performed at the self-consistent Born approximation. Results for Landau level width and optical absorption are presented. A disorder activated forbidden transition becomes significant in the vicinity of crossings of Landau levels which belong to different subbands. A study of the time dependent survival probability in the lowest Landau level of the excited subband is performed. It is shown that at resonance the population relaxation occurs in a subpicosecond scale.Comment: 7 pages, 8 figure

4,5-bis(benzoylsulfanyl)-1,3-dithiol-2-one

Peer reviewedPublisher PD

The linear growth rate of structure in Parametrized Post Friedmannian Universes

A possible solution to the dark energy problem is that Einstein's theory of general relativity is modified. A suite of models have been proposed that, in general, are unable to predict the correct amount of large scale structure in the distribution of galaxies or anisotropies in the Cosmic Microwave Background. It has been argued, however, that it should be possible to constrain a general class of theories of modified gravity by focusing on properties such as the growing mode, gravitational slip and the effective, time varying Newton's constant. We show that assuming certain physical requirements such as stability, metricity and gauge invariance, it is possible to come up with consistency conditions between these various parameters. In this paper we focus on theories which have, at most, 2nd derivatives in the metric variables and find restrictions that shed light on current and future experimental constraints without having to resort to a (as yet unknown) complete theory of modified gravity. We claim that future measurements of the growth of structure on small scales (i.e. from 1-200 h^{-1} Mpc) may lead to tight constraints on both dark energy and modified theories of gravity.Comment: 15 Pages, 11 Figure

Eikonal profile functions and amplitudes for pp\rm pp and pˉp\bar{\rm p}{\rm p} scattering

The eikonal profile function $J(b)$ obtained from the Model of the Stochastic Vacuum is parametrized in a form suitable for comparison with experiment. The amplitude and the extended profile function (including imaginary and real parts) are determined directly from the complete pp and $\bar{\rm p}$p elastic scattering data at high energies. Full and accurate representation of the data is presented, with smooth energy dependence of all parameters. The changes needed in the original profile function required for description of scattering beyond the forward direction are described.Comment: Latex, 28 pages and 16 figure

Mass for Plasma Photons from Gauge Symmetry Breaking

We derive the effective masses for photons in unmagnetized plasma waves using a quantum field theory with two vector fields (gauge fields). In order to properly define the quantum field degrees of freedom we re-derive the classical wave equations on light-front gauge. This is needed because the usual scalar potential of electromagnetism is, in quantum field theory, not a physical degree of freedom that renders negative energy eigenstates. We also consider a background local fluid metric that allows for a covariant treatment of the problem. The different masses for the longitudinal (plasmon) and transverse photons are in our framework due to the local fluid metric. We apply the mechanism of mass generation by gauge symmetry breaking recently proposed by the authors by giving a non-trivial vacuum-expectation-value to the second vector field (gauge field). The Debye length $\lambda_D$ is interpreted as an effective compactification length and we compute an explicit solution for the large gauge transformations that correspond to the specific mass eigenvalues derived here. Using an usual quantum field theory canonical quantization we obtain the usual results in the literature. Although none of these ingredients are new to physicist, as far as the authors are aware it is the first time that such constructions are applied to Plasma Physics. Also we give a physical interpretation (and realization) for the second vector field in terms of the plasma background in terms of known physical phenomena. Addendum: It is given a short proof that equation (10) is wrong, therefore equations (12-17) are meaningless. The remaining results are correct being generic derivations for nonmagnetized plasmas derived in a covariant QFT framework.Comment: v1: 1+6 pages v2: Several discussions rewritten; Abstract rewritten; References added; v3: includes Addendu