24,199 research outputs found
Superfluidity in Three-species Mixture of Fermi Gases across Feshbach Resonances
In this letter a generalization of the BEC-BCS crossover theory to a
multicomponent superfluid is presented by studying a three-species mixture of
Fermi gas across two Feshbach resonances. At the BEC side of resonances, two
kinds of molecules are stable which gives rise to a two-component Bose
condensate. This two-component superfluid state can be experimentally
identified from the radio-frequency spectroscopy, density profile and short
noise measurements. As approaching the BCS side of resonances, the
superfluidity will break down at some point and yield a first-order quantum
phase transition to normal state, due to the mismatch of three Fermi surfaces.
Phase separation instability will occur around the critical regime.Comment: 4 pages, 3 figures, revised versio
A Geometrical Test of the Cosmological Energy Contents Using the Lyman-alpha Forest
In this Letter we explore a version of the test of cosmological geometry
proposed by Alcock and Paczynski (1979), using observations of the Lyman-alpha
forest in the spectra of close quasar pairs. By comparing the correlations in
absorption in one quasar spectrum with correlations between the spectra of
neighboring quasars one can determine the relation of the redshift distance
scale to the angle distance scale at the redshift of the absorbers, . Since this relationship depends on the parameters of the cosmological
model, these parameters may be determined using the Lyman-alpha forest. While
this test is relatively insensitive to the density parameter in a
dust-dominated universe, it is more sensitive to the presence of a matter
component with large negative pressure (such as a cosmological constant
) and its equation of state. With only 25 pairs of quasar spectra at
angular separations , one can discriminate between an open universe () and an flat
(-dominated) universe at the level. The S/N can be enhanced
by considering quasar pairs at smaller angular separations, but requires proper
modeling of nonlinear redshift space distortions. Here the correlations and
redshift space distortions are modeled using linear theory.Comment: 13 pages, 2 ps figures, submitted to ApJ
Residual proton-neutron interactions and the scheme
We investigate the correlation between integrated proton-neutron interactions
obtained by using the up-to-date experimental data of binding energies and the
, the product of valence proton number and valence neutron
number with respect to the nearest doubly closed nucleus. We make corrections
on a previously suggested formula for the integrated proton-neutron
interaction. Our results demonstrate a nice, nearly linear, correlation between
the integrated p-n interaction and , which provides us
with a firm foundation of the applicability of the scheme
to nuclei far from the stability line.Comment: four pages, three figures, Physical Review C, in pres
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