284 research outputs found
Comment on "Acoustics of tachyon Fermi gas" [E. Trojan and G.V. Vlasov, arXiv:1103.2276 (hep-ph)]
In contrast to Trojan and Vlasov [arXiv:1103.2276 (hep-ph)], it is found that
an ideal Fermi gas of tachyons has a subluminous velocity of sound for any
particle density and, therefore, the causality condition for a tachyon gas
holds always true. Also, an ideal Fermi gas of tachyons never possesses an
exotic equation of state with the pressure exceeding the energy density.Comment: 1 page + Ref
Underbarrier nucleation kinetics in a metastable quantum liquid near the spinodal
We develop a theory in order to describe the effect of relaxation in a
condensed medium upon the quantum decay of a metastable liquid near the
spinodal at low temperatures. We find that both the regime and the rate of
quantum nucleation strongly depend on the relaxation time and its temperature
behavior. The quantum nucleation rate slows down with the decrease of the
relaxation time. We also discuss the low temperature experiments on cavitation
in normal He and superfluid He at negative pressures. It is the sharp
distinctions in the high frequency sound mode and in the temperature behavior
of the relaxation time that make the quantum cavitation kinetics in He and
He completely different in kind.Comment: 10 pages, 2 figure
U(1) and SU(2) quantum dissipative systems: The Caldeira-Leggett vs. the Amegaokar-Eckern-Sch\"on approaches
There are two paradigmatic frameworks for treating quantum systems coupled to
a dissipative environment: the Caldeira-Leggett and the
Ambegaokar-Eckern-Sch\"on approaches. Here we recall the differences between
them, and explain the consequences when each is applied to a zero dimensional
spin (possessing an SU(2) symmetry) in a dissipative environment (a dissipative
quantum dot near or beyond the Stoner instability point).Comment: Contribution for Leonid Keldysh 85 Festschrif
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