1p-f-14 ground-state energy of charged-boson and fermion system at high-density limit.greens function method.

秀夫 金沢, 光昭 宜野座

光昭 宜野座

Mitsuaki Ginoza, Hideo Kanazawa, 光昭 宜野座 +1 more

The neutral system consisting of charged-bosons and -fermions has been investigated in terms of density parameter expansion at the high-density limit. The ground state energy of this system is calculated and accords with the result obtained in our previous work. The elementary excitations in the system determined from the poles of the boson Green's function are the two collective excitations in the low momentum region : acoustic- and optical-phonon like. The life-time of the acoustic phonon approaches infinite as s/v_f →0 where s and v_f arc the sound velocity and Fermi velocity, respectively, while that of the optical pbonon is infinite.

Donald Wright

The ground-state energy of the charged Bose gas at high densities is determined by the method of Green's functions. The pair Hamiltonian of Girardeau and Arnowitt is used to calculate the Green's functions. The leading terms in the high-density expansion are found to agree exactly with those determined by Girardeau using a variational method.

Wenxing Nie, Hosho Katsura, Masaki Oshikawa

Leslie L. Foldy

The ground state energy and elementary excitations of a charged gas of bosons at high densities are examined by use of the method developed by Bogoliubov for boson gases. It is conjectured, but not herein established, that this method yields exact results in the high-density limit analogous to those obtained by Gell-Mann and Brueckner, and by Sawada, in the corresponding case of a charged fermion gas. The ground state energy is essentially correlation energy, and is therefore negative, and its magnitude varies as the one-fourth power of the density at high densities. The elementary excitations have for low momenta the energy appropriate to plasma waves, and for high momenta the energy appropriate to single-particle excitation. There is therefore an energy gap, suggesting that the gas is both a superfluid and a superconductor at low temperatures. At low densities the behavior of a charged gas is independent of statistics; hence, such a gap must disappear as the system is expanded.