594 research outputs found
Holographic Oddballs
The spectrum of the glueball with is computed using different
bottom-up holographic models of QCD. The results indicate a lowest-lying state
lighter than in the determination by other methods, with mass
GeV. The in-medium properties of this gluonium are investigated, and stability
against thermal and density effects is compared to other hadronic systems.
Production and decay modes are identified, useful for searching the
glueball.Comment: 16 pages, 9 figures, 3 table
On thermalization of a boost-invariant non Abelian plasma
Using a holographic method, we further investigate the relaxation towards the
hydrodynamic regime of a boost-invariant non-Abelian plasma taken
out-of-equilibrium. In the dual description, the system is driven
out-of-equilibrium by boundary sourcing, a deformation of the boundary metric,
as proposed by Chesler and Yaffe. The effects of several deformation profiles
on the bulk geometry are investigated by the analysis of the corresponding
solutions of the Einstein equations. The time of restoration of the
hydrodynamic regime is investigated: setting the effective temperature of the
system at the end of the boundary quenching to MeV, the
hydrodynamic regime is reached after a lapse of time of (1 fm/c).Comment: 24 pages, 11 figures. Improved numerical analysis, one more appendix,
two new figures. To appear in JHE
Quarkonium dissociation in a far-from-equilibrium holographic setup
The real-time dissociation of the heavy quarkonium in a strongly coupled
boost-invariant non-Abelian plasma relaxing towards equilibrium is analyzed in
a holographic framework. The effects driving the plasma out of equilibrium are
described by boundary quenching, impulsive variations of the boundary metric.
Quarkonium is represented by a classical string with endpoints kept close to
the boundary. The evolution of the string profile is computed in the
time-dependent geometry, and the dissociation time is evaluated for different
configurations with respect to the direction of the plasma expansion.
Dissociation occurs fastly for the quarkonium placed in the transverse plane.Comment: 14 pages, 8 figures. References added. Matches the published versio
Application of a new processing method to post-LDL-apheresis data.
Our aim was to elaborate a method to optimise treatment intervals for the individual low-density
lipoprotein (LDL)-apheresis treated patients. After each treatment, plasma LDL concentrations show a
time-related increase with a decreasing speed until a maximum level.We searched to interpret the post-
LDL-apheresis experimental data trend as the physical process that produces the observed curve, so that
the fitting presupposed theoretical function is a direct consequence of the physic process, because to
establish the better time. Applying the proposed fitting method to a succession of 15 samples obtained
from the mean of six plasmapheresis executed on five different subjects, small estimate standard error
(5 mg/dl) and relative error (1.7%) with a dispersion evidently related to the experimental error were
observed. Obviously, applying the same method to a single case, the dispersion is more marked (relative
error ,5%), with a SE of 10â13 mg/dl, even though the aspect of a casual phenomenon is conserved.
Our physical interpretation appears to be a practical model to predict the LDL-rebound kinetic of the
single patient
Quarkonium dissociation in strongly coupled far-from-equilibrium matter: holographic description
Abstract The heavy quarkonium real-time dissociation in a strongly coupled non-Abelian matter relaxing to equilibrium is described in a holographic approach. Boundary sourcing, impulsive distortions of the boundary metric, are used to mimic effects driving the matter far-from-equilibrium. Quarkonium is represented by a string with endpoints kept close to the boundary, and its evolution in the time-dependent geometry is studied
Continuous and discontinuous phase transitions and partial synchronization in stochastic three-state oscillators
We investigate both continuous (second-order) and discontinuous (first-order)
transitions to macroscopic synchronization within a single class of discrete,
stochastic (globally) phase-coupled oscillators. We provide analytical and
numerical evidence that the continuity of the transition depends on the
coupling coefficients and, in some nonuniform populations, on the degree of
quenched disorder. Hence, in a relatively simple setting this class of models
exhibits the qualitative behaviors characteristic of a variety of considerably
more complicated models. In addition, we study the microscopic basis of
synchronization above threshold and detail the counterintuitive subtleties
relating measurements of time averaged frequencies and mean field oscillations.
Most notably, we observe a state of suprathreshold partial synchronization in
which time-averaged frequency measurements from individual oscillators do not
correspond to the frequency of macroscopic oscillations observed in the
population
Heavy quarkonium moving in a quark-gluon plasma
By means of effective field theory techniques, we study the modifications of some properties of weakly coupled heavy quarkonium states propagating through a quark-gluon plasma at temperatures much smaller than the heavy quark mass, mQ. Two different cases are considered, corresponding to two different hierarchies between the typical size of the bound state, r, the binding energy, E, the temperature, T, and the screening mass, mD. The first case corresponds to the hierarchy mQâ«1/râ«Tâ«Eâ«mD, relevant for moderate temperatures, and the second one to the hierarchy mQâ«Tâ«1/r, mDâ«E, relevant for studying the dissociation mechanism. In the first case we determine the perturbative correction to the binding energy and to the decay width of states with arbitrary angular momentum, finding that the width is a decreasing function of the velocity. A different behavior characterizes the second kinematical case, where the width of s-wave states becomes a nonmonotonic function of the velocity, increasing at moderate velocities and decreasing in the ultrarelativistic limit. We obtain a simple analytical expression of the decay width for Tâ«1/râ«mDâ«E at moderate velocities, and we derive the s-wave spectral function for the more general case Tâ«1/r, mDâ«E. A brief discussion of the possible experimental signatures as well as a comparison with the relevant lattice data are also presented
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