5 research outputs found
Equilibrium and stability properties of a coupled two-component Bose-Einstein condensate
The equilibrium and stability properties of a coupled two-component BEC is
studied using a variational method and the one-dimensional model of Williams
and collaborators. The variational parameters are the population fraction,
translation and scaling transformation of the condensate densities, assumed to
have a Gaussian shape. We study the equilibrium and stability properties as a
function of the strength of the laser field and the traps displacement. We find
many branches of equilibrium configurations, with a host of critical points. In
all cases, the signature of the onset of criticality is the collapse of a
normal mode which is a linear combination of the out of phase translation and
an in phase breathing oscillation of the condensate densities. Our calculations
also indicate that we have symmetry breaking effects when the traps are not
displacedComment: 13 pages,3 figure
Self-Consistent Quasi-Particle RPA for the Description of Superfluid Fermi Systems
Self-Consistent Quasi-Particle RPA (SCQRPA) is for the first time applied to
a more level pairing case. Various filling situations and values for the
coupling constant are considered. Very encouraging results in comparison with
the exact solution of the model are obtained. The nature of the low lying mode
in SCQRPA is identified. The strong reduction of the number fluctuation in
SCQRPA vs BCS is pointed out. The transition from superfluidity to the normal
fluid case is carefully investigated.Comment: 23 pages, 18 figures and 1 table, submitted to Phys. Rev.
Proton-neutron self-consistent quasiparticle random phase approximation within the O(5) model
The self-consistent quasiparticle random phase approximation (SCQRPA) within the O(5) model in the coupled proton-neutron representation is analyzed. The exact vacuum wave function is used to compute all involved matrix elements. A stability analysis of the stationary points is performed. A phase transition from the uncoupled to the coupled stable proton-neutron regime beyond the QRPA breakdown value of the particle-particle strength is evidenced. The excitation energies are close to the lowest stable exact eigenvalues given by the diagonalization procedure for all cases. The conditions for which the Ikeda sum rule is fulfilled for all values of the particle-particle strength are pointed out
Self-consistent random phase approximation within the O(5) model and Fermi transitions
By focusing on the notion of electronic document, this paper suggests some items to better take into account the scope of information sciences when building and using corpus-based terminologies. The notion of usage is a guideline that we follow to investigate both the way designed resources are used within target applications and the way they are built up, from texts that are them-selves considered as revealing linguistic regularities, that refer to the system use