INTERACTING MIXED SYSTEM OF BOSONS AND FERMIONS. I. SINGLE PARTICLE AND SOME COLLECTIVE EXCITATIONS IN A DILUTE MIXTURE OF $sup 4$He AND $sup 3$He AT VERY LOW TEMPERATURES
The single boson and the single fermion energy spectra are studied for a mixed interacting system of bosons and fermions in the zero temperature limit. A combined method of the Bogoliubov approximation for the bosons and the Random Phase Approximation (RPA) for the fermions is employed. For the dressed bosons excitations correspond to a strong coupling of single bosons to the collective motion of fermion particle-hole pairs. This coupling is, in important physical cases, capable of introducing a damping of the single boson states in the region of small momenta, i.e., of the phonons. The energy of such modes is a sensitive function of the effective boson-fermion interaction and of the density. The single fermion spectra of fermions dressed in boson-fermion pairs are similar in shape to those of the Hartree-Fock approximation; only the energy function E = E(p) is, respectively, shifted as a whole, and is slightly flattened out. A schematic pseudopotential and effective mass model is used as a numerical illustration for the case of the dilute liquid He/sup 4/-He/sup 3/ mixture. (auth)
- Research Organization:
- Universita, Bologna; and Istituto Nazionale di Fisica Nucleare, Rome
- NSA Number:
- NSA-17-026313
- OSTI ID:
- 4705106
- Journal Information:
- Nuovo Cimento (Italy) Divided into Nuovo Cimento A and Nuovo Cimento B, Vol. Vol: (10), 28; Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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