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Paper IPM / P / 6846  


Abstract:  
We critically examine the HartreeFockBogoliubov (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 infrareddivergent 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 HugenholtzPines relation for the chemical potential is needed to cancel an unphysical divergence. Exact cancellation of infrareddivergent terms is demonstrated in the HFB shift of the singleparticle 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 weakcoupling regime: these are the chemical potential, the condensate fraction, the normal and anomalous momentum distribution functions and the corresponding onebody density matrices, and the dispersion relation of singleparticle excitations.
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