Multi-connected Momentum Distribution and Fermion Condensation

TL;DR

This paper investigates how a Fermi liquid's ground state restructures beyond an instability point, revealing a transition from multi-connected momentum distributions to fermion condensation influenced by temperature and interaction strength.

Contribution

It introduces a detailed analysis of ground state rearrangements in strongly interacting Fermi liquids, highlighting the emergence of multi-connected distributions and their transition to fermion condensation.

Findings

Identification of two temperature regimes affecting the ground state structure.

Demonstration of the transition from multi-connected distributions to fermion condensate.

Numerical evidence of the critical interaction strength for rearrangement.

Abstract

The structure of the ground state beyond the instability point of the quasiparticle system with Fermi-step momentum distribution is studied within the model of a Fermi liquid with a strong repulsive interaction. A ground state rearrangement occurs as the interaction strength is increased beyond a definite critical value. Numerical investigation of the initial stage of this structural transition shows that there are two temperature regions, corresponding to different scenarios of the rearrangement. While for temperature T larger than some characteristic temperature T_0 the behaviour of the system is the same as that in the case of the fermion condensation, for T<T_0 the intermediate structure with multi-connected quasiparticle momentum distribution arises. The transition of this structure to the fermion condensate at increasing interaction strength is discussed.