Statistical repulsion on hyperons in two-color dense QCD

We investigate the onset of hyperons in baryonic (diquark) matter in two-color QCD ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:msub> <a:mrow> <a:mi>QC</a:mi> </a:mrow> <a:mrow> <a:mn>2</a:mn> </a:mrow> </a:msub> <a:mi mathvariant="normal">D</a:mi> </a:mrow> </a:math> ) by introducing heavy quark doublets that emulate strange quarks. An even number of flavors is chosen to construct a theory amenable to sign-problem-free lattice Monte Carlo simulations. To explore <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"> <d:mrow> <d:msub> <d:mrow> <d:mi>QC</d:mi> </d:mrow> <d:mrow> <d:mn>2</d:mn> </d:mrow> </d:msub> <d:mi mathvariant="normal">D</d:mi> </d:mrow> </d:math> 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 preoccupied 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.