41,188 research outputs found
Integrals of motion in the Many-Body localized phase
We construct a complete set of quasi-local integrals of motion for the
many-body localized phase of interacting fermions in a disordered potential.
The integrals of motion can be chosen to have binary spectrum , thus
constituting exact quasiparticle occupation number operators for the Fermi
insulator. We map the problem onto a non-Hermitian hopping problem on a lattice
in operator space. We show how the integrals of motion can be built, under
certain approximations, as a convergent series in the interaction strength. An
estimate of its radius of convergence is given, which also provides an estimate
for the many-body localization-delocalization transition. Finally, we discuss
how the properties of the operator expansion for the integrals of motion imply
the presence or absence of a finite temperature transition.Comment: 65 pages, 12 figures. Corrected typos, added reference
Studying the infrared region in Landau gauge QCD
We report on the progress we made in studying the infrared behavior of the
ghost and gluon dressing functions in Landau gauge. Related to this we also
investigate a running coupling given in terms of those functions and compare
our results to those coming from the Dyson-Schwinger approach. We present first
numerical results for the SU(3) ghost-ghost-gluon vertex renormalization
constant. In addition the spectrum of low-lying eigenvalues and eigenfunctions
of the Faddeev-Popov operator is determined. The saturation of the ghost
propagator in terms of those eigenvalues and eigenmodes is discussed at lower
momenta.Comment: 6 pages, 4 figures, talk presented at Lattice 2005 (Topology and
Confinement
The influence of Gribov copies on the gluon and ghost propagator
The dependence of the gluon and ghost propagator in pure SU(3) gauge theory
on the choice of Gribov copies in Landau gauge is studied. Simulations were
performed on several lattice sizes at =5.8, 6.0 and 6.2. In the infrared
region the ghost propagator turns out to depend on the choice, while the impact
on the gluon propagator is not resolvable. Also the eigenvalue distribution of
the Faddeev-Popov operator is sensitive to Gribov copies.Comment: Talk presented at Quark Confinement and the Hadron Spectrum VI,
Villasimius, Sardinia, Italy, September 21-25, 2004, 3 pages, 2 figure
A Modified "Bottom-up" Thermalization in Heavy Ion Collisions
In the initial stage of the bottom-up picture of thermalization in heavy ion
collisions, the gluon distribution is highly anisotropic which can give rise to
plasma instability. This has not been taken account in the original paper. It
is shown that in the presence of instability there are scaling solutions, which
depend on one parameter, that match smoothly onto the late stage of bottom-up
when thermalization takes place.Comment: 8 pages and 1 embedded figure, talk presented at the Workshop on
"Quark-Gluon Plasma Thermalization", Vienna, Austria, 10-12 August 200
Confinement potential in dual Monopole Nambu-Jona-Lasinio model with dual Dirac strings
Interquark confinement potential is calculated in the dual Monopole
Nambu-Jona-Lasinio model with dual Dirac strings as a functional of a dual
Dirac string length. The calculation is carried out by the explicit integration
over quantum fluctuations of a dual-vector field (monopole-antimonopole
collective excitation) around the Abrikosov flux line and string shape
fluctuations. The contribution of the scalar field (monopole-antimonopole
collective excitation) exchange is taken into account in the tree approximation
due to the London limit regime.Comment: 10 pages, Latex, no figure
Quantum and string shape fluctuations in the dual Monopole Nambu-Jona-Lasinio model with dual Dirac strings
The magnetic monopole condensate is calculated in the dual Monopole
Nambu-Jona-Lasinio model with dual Dirac strings suggested in Refs.[1,2] as a
functional of the dual Dirac string shape. The calculation is carried out in
the tree approximation in the scalar monopole-antimonopole collective
excitation field. The integration over quantum fluctuations of the dual-vector
monopole-antimonopole collective excitation field around the Abrikosov flux
line and string shape fluctuations are performed explicitly. We claim that
there are important contributions of quantum and string shape fluctuations to
the magnetic monopole condensate.Comment: 19 pages, Latex, 2 figure
The core helium flash revisited: II. Two and three-dimensional hydrodynamic simulations
We study turbulent convection during the core helium flash close to its peak
by comparing the results of two and three-dimensional hydrodynamic simulations.
We use a multidimensional Eulerian hydrodynamics code based on
state-of-the-art numerical techniques to simulate the evolution of the helium
core of a Pop I star.
Our three-dimensional hydrodynamic simulations of the evolution of a star
during the peak of the core helium flash do not show any explosive behavior.
The convective flow patterns developing in the three-dimensional models are
structurally different from those of the corresponding two-dimensional models,
and the typical convective velocities are smaller than those found in their
two-dimensional counterparts. Three-dimensional models also tend to agree
better with the predictions of mixing length theory. Our hydrodynamic
simulations show the presence of turbulent entrainment that results in a growth
of the convection zone on a dynamic time scale. Contrary to mixing length
theory, the outer part of the convection zone is characterized by a
sub-adiabatic temperature gradient.Comment: 19 pages, 18 figure
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