Strangeon Matter: from Stars to Nuggets

Abstract

The fact that strange sea quarks are abundant in the nucleons, but with zero net strangeness, is of great importance for understanding the nature of matter condensed by the strong interaction, particularly in the context of the ``gigantic nucleus'' formed by the gravitational collapse of an evolved massive star. We hypothesize that the basic unit of bulk strong matter with the light-flavor symmetry of valence quarks is ``strangeon'', which is the counterpart of the nucleon found in atomic nuclei. In addition to strangeon stars (SnSs) with large baryon number of $A\approx 10^{57}$, strange nuggets (SnNs) with $A\gtrsim 10^{10}$ could also exist in the Universe. Both the SnS and the SnN are explained, with attention to their observational evidence.

Comments: 13 pages, 7 figures, paper presented at the conference "Compact Stars in the QCD Phase diagram 2024", 7 - 11 October 2024, Yukawa Institute for Theoretical Physics (YITP), Kyoto, Japan. Submitted to the special issue "Compact Stars in the QCD Phase Diagram 2024" of the journal Universe