172 research outputs found
Liouville-von Neumann approach and time-dependent Gaussian approximation
We show that Liouville-von Neumann approach to quantum mechanical systems,
which demands the existence of invariant operators, reproduces the
time-dependent variational Gaussian approximation. We find the effective action
of the time-dependent systems and show that many aspects of the dynamics are
independent of the details of time evolution, e.g., the squeezing of the
wave-function is determined by the effective potential of the final stage of
time-evolution.Comment: 10 pages, 2 figure
Casimir energy of a spherical shell in Minkowski spacetime
We study the Casimir energy of a spherical shell of radius in
-Minkowski spacetime for a complex field with an asymmetric ordering
and obtain the energy up to . We show that the vacuum breaks
particle and anti-particle symmetry if one requires the spectra to be
consistent with the blackbody radiation at the commutative limit.Comment: 23 pages, 3 figures, add more analysi
Post Gaussian effective potential in the Ginzburg Landau theory of superconductivity
The post Gaussian effective potential in D=3 dimensions and the Gaussian
effective potential in D=2+epsilon are evaluated for the Ginzburg-Landau theory
of superconductivity. It is shown that, the next order correction to the
Gaussian approximation of the Ginzburg-Landau parameter (kappa) is significant,
whereas contribution from the two dimensionality is rather small. This strongly
indicates that strong correlation plays a more dominant role than the two
dimensionality does in high T_c superconductivity.Comment: 15 pages, RevTeX, 4 figures, minor changes has been mad
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