The Scalar Hexaquark $uuddss$: a Candidate to Dark Matter?

Abstract

It is conventionally argued that Dark Matter (DM) has a non-baryonic nature, but if we assume that DM was frozen out before primordial nucleosynthesis and could not significantly impact primordial abundances this argument may be evaded. Then a hypothetical $SU(3)$ flavor-singlet, highly symmetric, deeply bound neutral scalar hexaquark $\mathrm{S}=uuddss$, which due to its features has escaped from experimental detection so far, may be considered as a candidate for a baryonic DM. In the present work we calculate the mass and coupling constant of the scalar six-quark particle $\mathrm{S}$ by means of the QCD sum rule method. Our predictions for its mass are $ m_{S}=1180_{-26}^{+40}~\mathrm{MeV}$ ($m_s=95~\mathrm{MeV}$) and $ \widetilde {m}_{S}=1239_{-28}^{+42}~\mathrm{MeV}$ ($m_s=128~\mathrm{MeV}$). Although these values of mass would produce thermally the cosmological DM abundance, existence of this state may contradict to stability of the oxygen nuclei, which requires further thorough analysis.