47,821 research outputs found
Structure and stability of quasi-two-dimensional boson-fermion mixtures with vortex-antivortex superposed states
We investigate the equilibrium properties of a quasi-two-dimensional
degenerate boson-fermion mixture (DBFM) with a bosonic vortex-antivortex
superposed state (VAVSS) using a quantum-hydrodynamic model. We show that,
depending on the choice of parameters, the DBFM with a VAVSS can exhibit rich
phase structures. For repulsive boson-fermion (BF) interaction, the
Bose-Einstein condensate (BEC) may constitute a petal-shaped "core" inside the
honeycomb-like fermionic component, or a ring-shaped joint "shell" around the
onion-like fermionic cloud, or multiple segregated "islands" embedded in the
disc-shaped Fermi gas. For attractive BF interaction just below the threshold
for collapse, an almost complete mixing between the bosonic and fermionic
components is formed, where the fermionic component tends to mimic a bosonic
VAVSS. The influence of an anharmonic trap on the density distributions of the
DBFM with a bosonic VAVSS is discussed. In addition, a stability region for
different cases of DBFM (without vortex, with a bosonic vortex, and with a
bosonic VAVSS) with specific parameters is given.Comment: 8 pages,5 figure
The gravitational time delay in the field of a slowly moving body with arbitrary multipoles
We calculate the time delay of light in the gravitational field of a slowly
moving body with arbitrary multipoles (mass and spin multipole moments) by the
Time-Transfer-Function (TTF) formalism. The parameters we use, first introduced
by Kopeikin for a gravitational source at rest, make the integration of the TTF
very elegant and simple. Results completely coincide with expressions from the
literature. The results for a moving body (with constant velocity) with
complete multipole-structure are new, according to our knowledge.Comment: 9 pages, no figure
Polarized laser-wakefield-accelerated kiloampere electron beams
High-flux polarized particle beams are of critical importance for the
investigation of spin-dependent processes, such as in searches of physics
beyond the Standard Model, as well as for scrutinizing the structure of solids
and surfaces in material science. Here we demonstrate that kiloampere polarized
electron beams can be produced via laser-wakefield acceleration from a gas
target. A simple theoretical model for determining the electron beam
polarization is presented and supported with self-consistent three-dimensional
particle-in-cell simulations that incorporate the spin dynamics. By
appropriately choosing the laser and gas parameters, we show that the
depolarization of electrons induced by the laser-wakefield-acceleration process
can be as low as 10%. Compared to currently available sources of polarized
electron beams, the flux is increased by four orders of magnitude.Comment: 6 pages, 3 figure
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