294 research outputs found
Hadron Resonance Gas Model with Induced Surface Tension
Here we present a physically transparent generalization of the multicomponent
Van der Waals equation of state in the grand canonical ensemble. For the
one-component case the third and fourth virial coefficients are calculated
analytically. It is shown that an adjustment of a single model parameter allows
us to reproduce the third and fourth virial coefficients of the gas of hard
spheres with small deviations from their exact values. A thorough comparison of
the compressibility factor and speed of sound of the developed model with the
one and two component Carnahan-Starling equation of state is made. It is shown
that the model with the induced surface tension is able to reproduce the
results of the Carnahan-Starling equation of state up to the packing fractions
0.2-0.22 at which the usual Van der Waals equation of state is inapplicable. At
higher packing fractions the developed equation of state is softer than the gas
of hard spheres and, hence, it breaks causality in the domain where the
hadronic description is expected to be inapplicable. Using this equation of
state we develop an entirely new hadron resonance gas model and apply it to a
description of the hadron yield ratios measured at AGS, SPS, RHIC and ALICE
energies of nuclear collisions. The achieved quality of the fit per degree of
freedom is about 1.08. We confirm that the strangeness enhancement factor has a
peak at low AGS energies, while at and above the highest SPS energy of
collisions the chemical equilibrium of strangeness is observed. We argue that
the chemical equilibrium of strangeness, i.e. , observed
above the center of mass collision energy 4.3 GeV may be related to the
hadronization of quark gluon bags which have the Hagedorn mass spectrum, and,
hence, it may be a new signal for the onset of deconfinement
Influence of zonal flows on unstable drift modes in ETG turbulence
The linear instability of the electron temperature gradient (ETG) driven
modes in the presence of zonal flows is investigated. Random and deterministic
- like profiles of the zonal flow are considered. It is shown that the
presence of shearing by zonal flows can stabilize the linear instability of ETG
drift modes
Nonlocal surface dipoles and vortices
We predict the existence and address the stability of two-dimensional surface
solitons featuring topologically complex shapes, including dipoles, vortices,
and bound states of vortex solitons, at the interface of nonlocal thermal
media. Unlike their counterparts in bulk media, surface dipoles are found to be
stable in the entire existence domain. Surface vortices are found to exhibit
strongly asymmetric intensity and phase distributions, and are shown to be
stable, too. Bound states of surface vortex solitons belong to a novel class of
surface solitons having no counterparts in bulk media. Such states are found to
be stable provided that their energy flow does not exceed an upper threshold.
Our findings constitute the first known example of topologically complex
solitons located at nonlocal two-dimensional interfaces.Comment: 20 pages, 5 figures, to appear in Phys. Rev.
p-wave superfluidity in mixtures of ultracold Fermi and spinor Bose gases
We reveal that the p-wave superfluid can be realized in a mixture of
fermionic and F=1 bosonic gases. We derive a general set of the gap equations
for gaps in the s- and p-channels. It is found that the spin-spin bose-fermi
interactions favor the p-wave pairing and naturally suppress the pairing in the
s-channel. The gap equations for the polar phase of p-wave superfluid fermions
are numerically solved. It is shown that a pure p-wave superfluid can be
observed in a well-controlled environment of atomic physics.Comment: 6 pages, 2 figure
New limit on the mass of 9.4-keV solar axions emitted in an M1 transition in Kr nuclei
A search for resonant absorption of the solar axion by nuclei
was performed using the proportional counter installed inside the
low-background setup at the Baksan Neutrino Observatory. The obtained model
independent upper limit on the combination of isoscalar and isovector
axion-nucleon couplings allowed us to set
the new upper limit on the hadronic axion mass of eV (95\%
C.L.) with the generally accepted values =0.5 and =0.56.Comment: 5 pages, 2 figures, Proceedings of the 10th Patras Workshop on
Axions, WIMPs and WISP 29 June - 4 July 2014, CERN, Geneva, Switzerlan
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