74,681 research outputs found
Mott-insulator phases of non-locally coupled 1D dipolar Bose gases
We analyze the Mott-insulator phases of dipolar bosonic gases placed in
neighboring but unconnected 1D traps. Whereas for short-range interactions the
1D systems are independent, the non-local dipole-dipole interaction induces a
direct Mott-insulator to pair-superfluid transition which significantly
modifies the boundaries of the lowest Mott-insulator phases. The lowest
boundary of the lowest Mott regions becomes progressively constant as a
function of the hopping rate, eventually inverting its slope, leading to a
re-entrant configuration which is retained in 2D. We discuss the consequences
of this effect on the spatial Mott-insulator plateaux in experiments with
additional harmonic confinement, showing that anti-intuitively the plateaux may
become wider for increasing hopping. Our results are also applicable to
non-dipolar boson-boson mixtures.Comment: 4 pages, 4 eps figures; minor changes, reference adde
Dynamical instabilities in density-dependent hadronic relativistic models
Unstable modes in asymmetric nuclear matter (ANM) at subsaturation densities
are studied in the framework of relativistic mean-field density-dependent
hadron models. The size of the instabilities that drive the system are
calculated and a comparison with results obtained within the non-linear Walecka
model is presented. The distillation and anti-distillation effects are
discussed.Comment: 8 pages, 8 Postscript figures. Submitted for publication in Phys.
Rev.
Out-of-equilibrium states and quasi-many-body localization in polar lattice gases
The absence of energy dissipation leads to an intriguing out-of-equilibrium
dynamics for ultracold polar gases in optical lattices, characterized by the
formation of dynamically-bound on-site and inter-site clusters of two or more
particles, and by an effective blockade repulsion. These effects combined with
the controlled preparation of initial states available in cold gases
experiments can be employed to create interesting out-of-equilibrium states.
These include quasi-equilibrated effectively repulsive 1D gases for attractive
dipolar interactions and dynamically-bound crystals. Furthermore,
non-equilibrium polar lattice gases can offer a promising scenario for the
study of many-body localization in the absence of quenched disorder. This
fascinating out-of-equilibrium dynamics for ultra-cold polar gases in optical
lattices may be accessible in on-going experiments.Comment: 5+1 pages, 4+1 figure
A square-well model for the structural and thermodynamic properties of simple colloidal systems
A model for the radial distribution function of a square-well fluid of
variable width previously proposed [S. B. Yuste and A. Santos, J. Chem. Phys.
{\bf 101}, 2355 (1994)] is revisited and simplified. The model provides an
explicit expression for the Laplace transform of , the coefficients
being given as explicit functions of the density, the temperature, and the
interaction range. In the limits corresponding to hard spheres and sticky hard
spheres the model reduces to the analytical solutions of the Percus-Yevick
equation for those potentials. The results can be useful to describe in a fully
analytical way the structural and thermodynamic behavior of colloidal
suspensions modeled as hard-core particles with a short-range attraction.
Comparison with computer simulation data shows a general good agreement, even
for relatively wide wells.Comment: 23 pages, 10 figures; Figs. 4 and 5 changed, Fig. 6 new; to be
published in J. Chem. Phy
Searching for a dark matter coupling to the Standard Model with a Stueckelberg extension
We investigate a double extension to the Standard Model (SM). A first
extension introduces, via minimal coupling, a massive boson. This enlarged
SM is coupled to a dark matter sector through the Stueckelberg mechanism by a
boson. However, the boson does not interact directly with the SM
fermions. In our study, we found that the is a massless photon-like
particle in dark sector. Constraints on the mass for and corrections to
mass are obtained.Comment: Presented at IWARA 2011. "Fifth International Workshop on Astronomy
and Relativistic Astrophysics" Jo\~ao Pessoa, Brazil, October 9 to 12, 201
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