614 research outputs found
Temperature dependence in random matrix models with pairing condensates
We address a number of issues raised by a manuscript of Klein, Toublan, and
Verbaarschot (hep-ph/0405180) in which the authors introduce a random matrix
model for QCD with two colors, two flavors, and fermions in the fundamental
representation. Their inclusion of temperature terms differs from the approach
adopted in previous work on this problem (Phys. Rev. D 64, 074016 (2001).) We
demonstrate that the two approaches are related by a transformation that leaves
the thermodynamic potential invariant and which therefore has no effect on
physical observables.Comment: 8 pages, revtex4. v2: typos corrected in reference
Use of 2G coated conductors for efficient shielding of DC magnetic fields
This paper reports the results of an experimental investigation of the
performance of two types of magnetic screens assembled from YBa2Cu3O7-d (YBCO)
coated conductors. Since effective screening of the axial DC magnetic field
requires the unimpeded flow of an azimuthal persistent current, we demonstrate
a configuration of a screening shell made out of standard YBCO coated conductor
capable to accomplish that. The screen allows the persistent current to flow in
the predominantly azimuthal direction at a temperature of 77 K. The persistent
screen, incorporating a single layer of superconducting film, can attenuate an
external magnetic field of up to 5 mT by more than an order of magnitude. For
comparison purposes, another type of screen which incorporates low critical
temperature quasi-persistent joints was also built. The shielding technique we
describe here appears to be especially promising for the realization of large
scale high-Tc superconducting screens.Comment: 8 pages, 3 figure
Random matrix study of the phase structure of QCD with two colors
We apply a random matrix model to the study of the phase diagram of QCD with two colors, two flavors, and a small quark mass. Although the effects of temperature are only included schematically, this model reproduces most of the ground state predictions of chiral perturbation theory and also gives a qualitative picture of the phase diagram at all temperatures. It leads, however, to an unphysical behavior of the chiral order parameter and the baryon density in vacuum and does not support diquark condensation at arbitrarily high densities. A better treatment of temperature dependence leads to correct vacuum and small temperature properties. We compare our results at both high and low densities with the results of microscopic calculations using the Nambu-Jona-Lasinio model and discuss the effects of large momentum scales on the variations of condensation fields with chemical potential
Values, value conflict and stress the prediction of stress by values and value conflict
The aim of this paper was to investigate the relationship between stress, values, and value conflict. Data collected from 400 people working in a wide variety of companies in Flanders indicated that the values openness to change, conservation, self-transcendence, self-enhancement, and value conflict were important predictors of stress. Participants open to change reported less stress, while respondents scoring high on conservation, self-enhancement, and self-transcendence perceived more stress. People reporting high value conflict also experienced more stress. Separate analyses for the male and female subsamples demonstrated that sex differences regarding the relationship between the four value types and stress cast new light on the findings for the total sample. The article concludes with a discussion of the results and future research directions
Values, value conflict and stress the prediction of stress by values and value conflict
The aim of this paper was to investigate the relationship between stress, values, and value conflict. Data collected from 400 people working in a wide variety of companies in Flanders indicated that the values openness to change, conservation, self-transcendence, self-enhancement, and value conflict were important predictors of stress. Participants open to change reported less stress, while respondents scoring high on conservation, self-enhancement, and self-transcendence perceived more stress. People reporting high value conflict also experienced more stress. Separate analyses for the male and female subsamples demonstrated that sex differences regarding the relationship between the four value types and stress cast new light on the findings for the total sample. The article concludes with a discussion of the results and future research directions
Diquark and Pion Condensation in Random Matrix Models for two-color QCD
We introduce a random matrix model with the symmetries of QCD with two colors
at nonzero isospin and baryon chemical potentials and temperature. We analyze
its phase diagram and find phases with condensation of pion and diquark states
in addition to the phases with spontaneously broken chiral symmetries. In the
limit of small chemical potentials and quark masses, we reproduce the mean
field results obtained from chiral Lagrangians. As in the case of QCD with
three colors, the presence of two chemical potentials breaks the flavor
symmetry and leads to phases that are characterized by different behaviors of
the chiral condensates for each flavor. In particular, the phase diagram we
obtain is similar to QCD with three colors and three flavors of quarks of equal
masses at zero baryon chemical potential and nonzero isospin and strange
chemical potentials. A tricritical point of the superfluid transitions found in
lattice calculations and from an analysis in terms of chiral Lagrangians does
not appear in the random matrix model. Remarkably, at fixed isospin chemical
potential, for the regions outside of the superfluid phases, the phase diagram
in the temperature - baryon chemical potential plane for two colors and three
colors are qualitatively the same.Comment: 19 pages, 7 figures, RevTeX
Classical analogy for the deflection of flux avalanches by a metallic layer
Sudden avalanches of magnetic flux bursting into a superconducting sample
undergo deflections of their trajectories when encountering a conductive layer
deposited on top of the superconductor. Remarkably, in some cases flux is
totally excluded from the area covered by the conductive layer. We present a
simple classical model that accounts for this behaviour and considers a
magnetic monopole approaching a semi-infinite conductive plane. This model
suggests that magnetic braking is an important mechanism responsible for
avalanche deflection.Comment: 14 pages, 5 figure
Thermodynamics of the \phi^4 theory in tadpole approximation
Relying on the Luttinger-Ward theorem we derive a thermodynamically
selfconsistent and scale independent approximation of the thermodynamic
potential for the scalar theory in the tadpole approximation. The
resulting thermodynamic potential as a function of the temperature is similar
to the one of the recently proposed screened perturbation theory.Comment: 6 pages, including 1 eps figur
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