The self-consistent field model for Fermi systems with account of three-body interactions

TL;DR

This paper develops a microscopic self-consistent field model for Fermi systems incorporating three-body interactions, deriving formulas for effective mass and equation of state, and analyzing their effects on system stability and quasiparticle spectra.

Contribution

It introduces a new approach to include nonlocal three-body forces in the self-consistent field model for Fermi systems, extending understanding of their thermodynamics and stability.

Findings

Three-body interactions do not contribute if delta-like; nonlocality is essential.

Repulsive three-body forces extend the stability region of the system.

Effective mass and pressure are calculated for semi-transparent sphere potential.

Abstract

On the basis of a microscopic model of self-consistent field, the thermodynamics of the many-particle Fermi system at finite temperatures with account of three-body interactions is built and the quasiparticle equations of motion are obtained. It is shown that the delta-like three-body interaction gives no contribution into the self-consistent field, and the description of three-body forces requires their nonlocality to be taken into account. The spatially uniform system is considered in detail, and on the basis of the developed microscopic approach general formulas are derived for the fermion's effective mass and the system's equation of state with account of contribution from three-body forces. The effective mass and pressure are numerically calculated for the potential of "semi-transparent sphere" type at zero temperature. Expansions of the effective mass and pressure in powers of density are obtained. It is shown that, with account of only pair forces, the interaction of repulsive character reduces the quasiparticle effective mass relative to the mass of a free particle, and the attractive interaction raises the effective mass. The question of thermodynamic stability of the Fermi system is considered and the three-body repulsive interaction is shown to extend the region of stability of the system with the interparticle pair attraction. The quasiparticle energy spectrum is calculated with account of three-body forces.