The zero-temperature excitation spectrum Ek of a dense charged Bose gas with mass M and charge e is combined with Landau's quasiparticle model to derive the thermodynamic functions at low temperature. The tinite long-wavelength limit V,!$ = 0, (the plasma frequency) implies that the normal-fluid density p,,(T) and the specific heat both vanish like exp(--frQ&T)
as T-t 0. A microscopic calculation with the Bogolyubov approximation gives the low-temperature correction to the depletion n'(T) -n'(0) = #M-k(T).
The transverse current j(q) induced by a transverse vector potential A(q) is evaluated in the same Bogolyubov approximation. For the two cases examined (long wavelengths at T > 0 and short wavelengths at T = 0), j(q) reduces to the London form -Cp -p,(T)](e*/M"c)A(q). Nonlocal contributions to the zero-temperature integral kernel K(x -x') are of order n'/n and hence small in the high-density limit.
I. INTR~DuC~ON
A charged Bose gas in a uniform neutralizing background presents a challenge to many-body theorists, for it combines Bose condensation with the special difficulties arising from the long-range Coulomb interactions. In a charged Fermi gas, the Coulomb potential becomes tractable in the high-density limit [l], where the small parameter, conventionally known as rs , is the ratio of the interparticle spacing to the Bohr radius. Fortunately, the same limit also simplifies the corresponding Bose problem because the depletion of the single-particle mode becomes small as rS -+ 0. This model was first examined by Foldy [2], who used a Bogolyubov transformation [3] to determine the zero-temperature properties to leading order in rs . More recently, many authors [4-81 have extended the zero-temperature theory to find the next correction terms.
The finite-temperature behavior of many-body systems is also of great interest. Although such questions have been studied extensively for a neutral Bose gas