42,339 research outputs found
Ground-State Properties of a Rotating Bose-Einstein Condensate with Attractive Interaction
The ground state of a rotating Bose-Einstein condensate with attractive
interaction in a quasi-one-dimensional torus is studied in terms of the ratio
of the mean-field interaction energy per particle to the
single-particle energy-level spacing. The plateaus of quantized circulation are
found to appear if and only if with the lengths of the plateaus
reduced due to hybridization of the condensate over different angular-momentum
states.Comment: 4 pages, 2 figures, Accepted for publication in Physical Reveiw
Letter
Contractor decision making and incentive fee contracts
Contractor decision making and incentive fee contracts in procurement of complex weapons and space system
Does The Addition of a Duration Improve the L_iso - E_peak Relation For Gamma-Ray Bursts?
Firmani et al. proposed a new Gamma Ray Burst (GRB) luminosity relation that
showed a significant improvement over the L_iso-E_peak relation. The new
proposed relation simply modifies the E_peak value by multiplying it by a power
of T_0.45, where T_0.45 is a particular measure of the GRB duration. We begin
by reproducing the results of Firmani for his 19 bursts. We then test the
Firmani relation for the same 19 bursts except that we use independently
measured values for L_iso, T_0.45, and E_peak, and we find that the relation
deteriorates substantially. We further test the relation by using 60 GRBs with
measured spectroscopic redshifts, and find a relation that has a comparable
scatter as the original L_iso-E_peak relation. That is, a much larger sample of
bursts does not reproduce the small scatter as reported by Firmani et al.
Finally, we investigate whether the Firmani relation is improved by the use of
any of 32 measures of duration in place of T_0.45. The quality of each
alternative duration measure is evaluated with the root mean square of the
scatter between the observed and fitted logarithmic Liso values. Although we
find some durations yield slightly better results than T_0.45, the differences
between the duration measures are minimal. We find that the addition of a
duration does not add any significant improvement to the L_iso-E_peak relation.
We also present a simple and direct derivation of the Firmani relation from
both the L_iso-E_peak and Amati relations. In all we conclude that the Firmani
relation neither has an independent existence nor does it provide any
significant improvement on previously known relations that are simpler.Comment: ApJ in press, 17 pages, 3 figures, 3 table
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