37,282 research outputs found
Spinor Bose Condensates in Optical Traps
In an optical trap, the ground state of spin-1 Bosons such as Na,
K, and Rb can be either a ferromagnetic or a "polar" state,
depending on the scattering lengths in different angular momentum channel. The
collective modes of these states have very different spin character and spatial
distributions. While ordinary vortices are stable in the polar state, only
those with unit circulation are stable in the ferromagnetic state. The
ferromagnetic state also has coreless (or Skyrmion) vortices like those of
superfluid He-A. Current estimates of scattering lengths suggest that the
ground states of Na and Rb condensate are a polar state and a
ferromagnetic state respectively.Comment: 11 pages, no figures. email : [email protected]
Masses of Open-Flavour Heavy-Light Hybrids from QCD Sum-Rules
We use QCD Laplace sum-rules to predict masses of open-flavour heavy-light
hybrids where one of the hybrid's constituent quarks is a charm or bottom and
the other is an up, down, or strange. We compute leading-order, diagonal
correlation functions of several hybrid interpolating currents, taking into
account QCD condensates up to dimension-six, and extract hybrid mass
predictions for all , as well as explore possible
mixing effects with conventional quark-antiquark mesons. Within theoretical
uncertainties, our results are consistent with a degeneracy between the
heavy-nonstrange and heavy-strange hybrids in all channels. We find a
similar mass hierarchy of , , and states (a state
lighter than essentially degenerate and states) in both the
charm and bottom sectors, and discuss an interpretation for the states.
If conventional meson mixing is present the effect is an increase in the hybrid
mass prediction, and we estimate an upper bound on this effect.Comment: 24 pages, 8 figures. Mass predictions updated from previous version
to reflect corrected sign error in sum rule analysis. Mixing analysis and
examination of higher weight sum-rules added. To be published in JHE
Research on a non-destructive fluidic storage control device
Fluidic memory device with associated fluidic alpha numerical displa
Rapidly Rotating Fermi Gases
We show that the density profile of a Fermi gas in rapidly rotating potential
will develop prominent features reflecting the underlying Landau level like
energy spectrum. Depending on the aspect ratio of the trap, these features can
be a sequence of ellipsoidal volumes or a sequence of quantized steps.Comment: 4 pages, 1 postscript fil
Feshbach resonant scattering of three fermions in one-dimensional wells
We study the weak-tunnelling limit for a system of cold 40K atoms trapped in
a one-dimensional optical lattice close to an s-wave Feshbach resonance. We
calculate the local spectrum for three atoms at one site of the lattice within
a two-channel model. Our results indicate that, for this one-dimensional
system, one- and two-channel models will differ close to the Feshbach
resonance, although the two theories would converge in the limit of strong
Feshbach coupling. We also find level crossings in the low-energy spectrum of a
single well with three atoms that may lead to quantum phase transition for an
optical lattice of many wells. We discuss the stability of the system to a
phase with non-uniform density.Comment: 10 pages, 5 figure
Topological Excitations in Spinor Bose-Einstein Condensates
We investigate the properties of skyrmion in the ferromagnetic state of
spin-1 Bose-Einstein condensates by means of the mean-field theory and show
that the size of skyrmion is fixed to the order of the healing length. It is
shown that the interaction between two skyrmions with oppositely rotating spin
textures is attractive when their separation is large, following a unique
power-law behavior with a power of -7/2.Comment: 4 pages, 5 figure
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