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Paper   IPM / Physic / 6846
School of Physics
  Title:   Hartree-Fock-Bogoliubov Theory of A Charged Bose Gas at Finite Temperature
1.  A. Minguzzi
2.  M. P. Tosi
3.  B. Davoudi
  Status:   Published
  Journal: Phys. Rev. B
  No.:  48
  Vol.:  65
  Year:  2002
  Pages:   144507-1-7
  Supported by:  IPM
We critically examine the Hartree-Fock-Bogoliubov (HFB) solution of the equations of motion for condensate fluctuations in a weakly coupled plasma of charged bosons at finite temperature. Analytic expressions are derived for the first two infrared-divergent terms in both the momentum distribution of the noncondensate and the anomalous Bose correlation function at low momenta. Incorporation into the theory of the appropriate form of the Hugenholtz-Pines relation for the chemical potential is needed to cancel an unphysical divergence. Exact cancellation of infrared-divergent terms is demonstrated in the HFB shift of the single-particle excitation energy away from the Bogoliubov value at long wavelengths, with the residual terms raising it towards the plasma frequency at low temperature. Numerical illustrations are presented for a number of properties of the boson plasma as functions of temperature and density in the weak-coupling regime: these are the chemical potential, the condensate fraction, the normal and anomalous momentum distribution functions and the corresponding one-body density matrices, and the dispersion relation of single-particle excitations.

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