163,161 research outputs found
Accelerated battery-life testing - A concept
Test program, employing empirical, statistical and physical methods, determines service life and failure probabilities of electrochemical cells and batteries, and is applicable to testing mechanical, electrical, and chemical devices. Data obtained aids long-term performance prediction of battery or cell
Breakdown of Hydrodynamics in the Radial Breathing Mode of a Strongly-Interacting Fermi Gas
We measure the magnetic field dependence of the frequency and damping time
for the radial breathing mode of an optically trapped, Fermi gas of Li
atoms near a Feshbach resonance. The measurements address the apparent
discrepancy between the results of Kinast et al., [Phys. Rev. Lett. {\bf 92},
150402 (2004)] and those of Bartenstein et al., [Phys. Rev. Lett. {\bf 92},
203201 (2004)]. Over the range of magnetic field from 770 G to 910 G, the
measurements confirm the results of Kinast et al. Close to resonance, the
measured frequencies are in excellent agreement with predictions for a unitary
hydrodynamic gas. At a field of 925 G, the measured frequency begins to
decrease below predictions. For fields near 1080 G, we observe a breakdown of
hydrodynamic behavior, which is manifested by a sharp increase in frequency and
damping rate. The observed breakdown is in qualitative agreement with the sharp
transition observed by Bartenstein et al., at 910 G.Comment: 4 pages, 2 figures, 1 table. Revised in response to referees'
Comments. Published in PRA(R
Resonant Leptogenesis
We study the scenario of thermal leptogenesis in which the leptonic
asymmetries are resonantly enhanced through the mixing of nearly degenerate
heavy Majorana neutrinos that have mass differences comparable to their decay
widths. Field-theoretic issues arising from the proper subtraction of real
intermediate states from the lepton-number-violating scattering processes are
addressed in connection with an earlier developed resummation approach to
unstable particle mixing in decay amplitudes. The pertinent Boltzmann equations
are numerically solved after the enhanced heavy-neutrino self-energy effects on
scatterings and the dominant gauge-mediated collision terms are included. We
show that resonant leptogenesis can be realized with heavy Majorana neutrinos
even as light as about 1 TeV, in complete accordance with the current solar and
atmospheric neutrino data.Comment: 53 pages, LaTeX, 5 eps figures, improved Eq. (A.7) and clarifying
comments adde
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