2,078 research outputs found
Development of three dimensional constitutive theories based on lower dimensional experimental data
Most three dimensional constitutive relations that have been developed to
describe the behavior of bodies are correlated against one dimensional and two
dimensional experiments. What is usually lost sight of is the fact that
infinity of such three dimensional models may be able to explain these
experiments that are lower dimensional. Recently, the notion of maximization of
the rate of entropy production has been used to obtain constitutive relations
based on the choice of the stored energy and rate of entropy production, etc.
In this paper we show different choices for the manner in which the body stores
energy and dissipates energy and satisfies the requirement of maximization of
the rate of entropy production that leads to many three dimensional models. All
of these models, in one dimension, reduce to the model proposed by Burgers to
describe the viscoelastic behavior of bodies.Comment: 23 pages, 6 figure
The interstellar clouds of Adams and Blaauw revisited: an HI absorption study - I
This investigation is aimed at clarifying the nature of the interstellar gas
seen in absorption against bright O and B stars. Towards this end we have
obtained for the first time HI absorption spectra towards radio sources very
close to the lines of sight towards 25 bright stars previously studied. In this
paper we describe the selection criteria, the details regarding our
observations, and finally present the absorption spectra. In the accompanying
paper we analyse the results and draw conclusions.Comment: 20 pages, 12 figures, accepted by Journal of Astrophysics and
Astronom
Magnetic vortex in color-flavor locked quark matter
Within Ginzburg-Landau theory, we study the structure of a magnetic vortex in
color-flavor locked quark matter. This vortex is characterized by winding of
the SU(3) phase in color-flavor space, as well as by the presence of a
color-flavor unlocked condensate in the core. We estimate the upper and lower
critical fields and the critical Ginzburg-Landau parameter that distinguishes
between type I and type II superconductors.Comment: 8 pages, 1 figur
Broken-symmetry-adapted Green function theory of condensed matter systems:towards a vector spin-density-functional theory
The group theory framework developed by Fukutome for a systematic analysis of
the various broken symmetry types of Hartree-Fock solutions exhibiting spin
structures is here extended to the general many body context using spinor-Green
function formalism for describing magnetic systems. Consequences of this theory
are discussed for examining the magnetism of itinerant electrons in nanometric
systems of current interest as well as bulk systems where a vector spin-density
form is required, by specializing our work to spin-density-functional
formalism. We also formulate the linear response theory for such a system and
compare and contrast them with the recent results obtained for localized
electron systems. The various phenomenological treatments of itinerant magnetic
systems are here unified in this group-theoretical description.Comment: 17 page
Inhomogeneous phase of a Gluon Plasma at finite temperature and density
By considering the non-perturbative effects associated with the fundamental
modular region, a new phase of a Gluon Plasma at finite density is proposed. It
corresponds to the transition from glueballs to non-perturbative gluons which
condense at a non vanishing momentum. In this respect the proposed phase is
analogous to the color superconducting LOFF phase for fermionic systems.Comment: 5 pages, 2 figure
The Crystallography of Strange Quark Matter
Cold three-flavor quark matter at large (but not asymptotically large)
densities may exist as a crystalline color superconductor. We explore this
possibility by calculating the gap parameter Delta and free energy Omega(Delta)
for possible crystal structures within a Ginzburg-Landau approximation,
evaluating Omega(Delta) to order Delta^6. We develop a qualitative
understanding of what makes a crystal structure stable, and find two structures
with particularly large values of Delta and the condensation energy, within a
factor of two of those for the CFL phase known to characterize QCD at
asymptotically large densities. The robustness of these phases results in their
being favored over wide ranges of density and though it also implies that the
Ginzburg-Landau approximation is not quantitatively reliable, previous work
suggests that it can be trusted for qualitative comparisons between crystal
structures. We close with a look ahead at the calculations that remain to be
done in order to make contact with observed pulsar glitches and neutron star
cooling.Comment: 6 pages, 3 figures. Contribution to the proceedings of Strangeness in
Quark Matter 2006, UCLA. Talk given by Rishi Sharm
Topological Discrete Algebra, Ground State Degeneracy, and Quark Confinement in QCD
Based on the permutation group formalism, we present a discrete symmetry
algebra in QCD. The discrete algebra is hidden symmetry in QCD, which is
manifest only on a space-manifold with non-trivial topology. Quark confinement
in the presence of the dynamical quarks is discussed in terms of the discrete
symmetry algebra. It is shown that the quark deconfinement phase has the ground
state degeneracy depending on the topology of the space, which gives a
gauge-invariant distinction between the confinement and deconfinement phases.
We also point out that new quantum numbers relating to the fractional quantum
Hall effect exist in the deconfinement phase.Comment: 11 pages, 1 figur
Entanglement of Pure Two-Mode Gaussian States
The entanglement of general pure Gaussian two-mode states is examined in
terms of the coefficients of the quadrature components of the wavefunction. The
entanglement criterion and the entanglement of formation are directly evaluated
as a function of these coefficients, without the need for deriving local
unitary transformations. These reproduce the results of other methods for the
special case of symmetric pure states which employ a relation between squeezed
states and Einstein-Podolsky-Rosen correlations. The modification of the
quadrature coefficients and the corresponding entanglement due to application
of various optical elements is also derived.Comment: 12 page
The nature of the long time decay at a second order transition point
We show that at a second order phase transition, of \phi^4 like system, a
necessary condition for streched exponential decay of the time structure factor
is obeyed. Using the ideas presented in this proof a crude estimate of the
decay of the structure factor is obtained and shown to yield stretched
exponential decay under very reasonable conditions.Comment: 7 page
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