Statistical repulsion on hyperons in two-color dense QCD

TL;DR

This paper studies how hyperons appear in two-color dense QCD by modeling quark interactions and finds that repulsive effects delay hyperon formation compared to simple hadronic estimates.

Contribution

It introduces a model with light and heavy quarks interacting via diquarks, revealing the repulsive effects delaying hyperon onset in dense matter.

Findings

Hyperons appear at higher densities than hadronic estimates suggest.

Light quark Pauli blocking induces effective repulsion among baryons.

Hyperon onset is significantly delayed due to quark-level Pauli effects.

Abstract

We investigate the onset of hyperons in baryonic (diquark) matter in two-color QCD (QC$_2$D) by introducing heavy quark doublets that emulate strange quarks. An even number of flavors is required to avoid the sign problem in lattice Monte Carlo simulations. To explore QC$_2$D matter containing both light and heavy quarks, we construct a model in which quarks interact with light-light, light-heavy (hyperonic), and heavy-heavy diquarks via Yukawa couplings. As the quark chemical potential increases, the light diquarks condense first and form baryonic matter, and this onset density can be understood in hadronic terms. In contrast, the onset density of hyperons is substantially higher than that estimated from the hadronic sector of the model. This shift reflects an effective repulsion among baryons induced by the pre-occupied light quarks. The Pauli blocking of light quarks suppresses the attractive diquark correlations responsible, in vacuum, for making hyperons lighter than the sum of the constituent light and heavy quark masses. Implications for three-color QCD are also briefly discussed.