Quark matter may not be strange

TL;DR

This paper suggests that under certain conditions, non-strange quark matter composed only of up and down quarks could be more stable than normal nuclei and strange quark matter, implying a new stable form of matter beyond the periodic table.

Contribution

It introduces a phenomenological model showing that non-strange quark matter can be energetically favored and stable for baryon numbers above approximately 300, challenging previous assumptions.

Findings

ud quark matter has lower energy per baryon than nuclei and SQM.

Stable ud quark matter exists only for baryon number A > 300.

Potential new stable matter beyond the periodic table.

Abstract

If quark matter is energetically favored over nuclear matter at zero temperature and pressure then it has long been expected to take the form of strange quark matter (SQM), with comparable amounts of $u$, $d$, $s$ quarks. The possibility of quark matter with only $u$, $d$ quarks ($ud$QM) is usually dismissed because of the observed stability of ordinary nuclei. However we find that $ud$QM generally has lower bulk energy per baryon than normal nuclei and SQM. This emerges in a phenomenological model that describes the spectra of the lightest pseudoscalar and scalar meson nonets. Taking into account the finite size effects, $ud$QM can be the ground state of baryonic matter only for baryon number $A>A_\textrm{min}$ with $A_\textrm{min}\gtrsim 300$. This ensures the stability of ordinary nuclei and points to a new form of stable matter just beyond the periodic table.