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ON PAIRS WITH A NON-ZERO ANGULAR MOMENTUM IN FERMI SYSTEMS

I. A. Privorotskiǐ

Published Apr 1, 1963• 0 citations
OpenAlex

Abstract

The properties of a Fermi system with a non-zero angular momentum pair interaction are investigated. Uncoupling of the three-particle Green function that yields a solution with isotropic and anisotropic gaps is suggested. It is shown that the solution with the anisotropic gap is asymptotically exact. The difficulties that appear in deriving the solutions with the isotropic gap are discussed. (auth)

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•Sep 1, 1959•0 citations
The properties of a Fermi system with a non-zero angular momentum pair interaction are investigated. Uncoupling of the three-particle Green function that yields a solution with isotropic and anisotropic gaps is suggested. It is shown that the solution with the anisotropic gap is asymptotically exact. The difficulties that appear in deriving the solutions with the isotropic gap are discussed. (auth)
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S>The solution of a compensation equation of dangerous graphs, for a system of interacting Fermi-particles, as an odd function of wave vectors is investigated. It is shown that this solution leads to the anomalous state, the energy of which is smaller than the energy of the normal state. The energy difference is equal to the binding energy of the pairs of fermions with parallel spin-moments. This anomalous state can exist in the presence of attractive Coulomb interactions. The elementary excitations are separated from the ground state by a gap the width of which depends on the direction of the wave vector. For the direction perpendicular to the spin direction, energy gap is zero and therefore the state cannot be superconducting. The binding energy of the pairs and the width of the energy gap are of the same order as in the theory based on the creation of pairs with antiparallel spin-moments, where in the expansion of the interaction term in spherical harmonics, the first coefficient is more than three times greater than the zero coefficient. In the absence of the magnetic field the total spin of a system is zero. In the presence of the magnetic field the total spinmore » differs from zero. The paramagnetic susceptibility is calculated. (auth)« less
An equation set describtng single particle excitations for excitation energies which are small compared with the chemical potential of the system can be obtained by investigating the analytical properties of the Green's functions and taking into account pair correlation. The equations are valid for an arbitrary interaction law. Equations are derived which describe the excited states of a system with a finite number of particles with an accuracy to terms of the order of N/sup -//sup 1//sup ///sup 3/ It is indicated how the results can be applied to real nuclei. (auth)
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