We derive via diagrammatic perturbation theory the scaling behavior of the condensate and superfluid mass density of a dilute Bose gas just below the condensation temperature, T(c). Sufficiently below T(c) particle excitations are described by mean field (Bogoliubov). Near T(c), however, mean field fails, and the system undergoes a second order phase transition, rather than first order as predi...

In this paper, we calculate theoretically the relaxation rates of hot, thermal and antinodal quasiparticles by using Fermi’s golden rule. The transition probabilities at low temperatures express in terms of Bogoliubov coefficients, singlet and triplet scattering amplitudes and dimensionless Landau parameters. The values of Landau parameters may be determined by comparison with the experimental ...

The paper deals with an approximate analysis of non-linear oscillation problems with slowly varying system parameters. From the differential equations for amplitude and phase, set up by the method of variation of parameters, the approximate solutions are obtained by using the generalized averaging method of Sinha and Srinivasan based on ultraspherical polynomial expansions. The Bogoliubov-Mitro...

We propose a new variational method which combines an excitation-energy sum rule and Fetter’s trial wave function to analytically find almost exact lowlying collective-mode frequencies of a trapped Bose-Einstein condensate. At zero temperature, our method gives excitation frequencies in excellent agreement with experimental results as well as numerical ones based on the Bogoliubov approximation...

The Bogoliubov transformation is generally derived in the context of identical bosons with the use of " second quantized " a and a † operators (or, equivalently, in field theory). Here, we show that the transformation , together with its characteristic energy spectrum, can also be derived within the Hilbert space of distinguishable particles, obeying Boltzmann statistics; in this derivation, or...