Four-particle condensate in strongly coupled fermion systems

TL;DR

This paper explores four-particle correlations in strongly coupled fermion systems, revealing a new quartetting condensate that can dominate over traditional pairing at certain densities, with implications for nuclear matter and semiconductors.

Contribution

It introduces a novel equation describing four-particle condensation, expanding understanding beyond traditional two-particle pairing models.

Findings

Four-particle condensation is favored below a critical density in nuclear matter.

A new equation for quartetting onset is derived.

Competition between pairing and quartetting is a general phenomenon.

Abstract

Four-particle correlations in fermion systems at finite temperatures are investigated with special attention to the formation of a condensate. Instead of the instability of the normal state with respect to the onset of pairing described by the Gorkov equation, a new equation is obtained which describes the onset of quartetting. Within a model calculation for symmetric nuclear matter, we find that below a critical density, the four-particle condensation (alpha-like quartetting) is favored over deuteron condensation (triplet pairing). This pairing-quartetting competition is expected to be a general feature of interacting fermion systems, such as the excition-biexciton system in excited semiconductors. Possible experimental consequences are pointed out.