Bulk Strong Matter: the Trinity

TL;DR

This paper explores the concept of bulk strong matter, including strange quark matter and strangeons, and discusses its potential manifestations in compact stars, cosmic rays, and dark matter, highlighting its significance in modern multi-messenger astronomy.

Contribution

It introduces the idea of bulk strong matter beyond atomic nuclei, emphasizing the possible existence of 3-flavoured matter like strangeons and strange quark matter, and their astrophysical implications.

Findings

Bulk strong matter could exist in various cosmic phenomena.

Strangeons and strange quark matter may be stable forms of 3-flavoured matter.

Implications for dark matter and compact stars are discussed.

Abstract

Our world is wonderful because of the normal but negligibly small baryonic part (i.e., atoms) although unknown dark matter and dark energy dominate the Universe. A stable atomic nucleus could be simply termed as ``strong matter'' since its nature is dominated by the fundamental strong interaction. Is there any other form of strong matter? Although nuclei are composed of 2-flavoured (i.e., up and down flavours of valence quarks) nucleons, it is conjectured that bulk strong matter could be 3-flavoured (with additional strange quarks) if the baryon number exceeds the critical value, $A_{\rm c}$, in which case quarks could be either free (so-called strange quark matter) or localized (in strangeons, coined by combining ``strange nucleon''). Bulk strong matter could be manifested in the form of compact stars, cosmic rays, and even dark matter. This trinity will be explained in this brief review, that may impact dramatically on today's physics, particularly in the era of multi-messenger astronomy after the discovery of gravitational wave.