A stable sexaquark is an appealing Dark Matter candidate. Simple statistical physics arguments, plus known QCD parameters (quark masses and QCD transition temperature), predicts the DM to baryon ratio after the QGP-hadron transition to be ~4.5 +- 1, in remarkable agreement with the observed value of 5.3 +- 0.1. (Contrary to the intuition of Kob and Turner, sexaquarks would not be dissociated in the low temperature hadronic phase, given reasonable estimates of their wave-function overlap with two baryons. Loopholes in the arguments of McDermott et al using SN1987a will also be pointed out.)
New stringent constraints on Dark Matter interactions will be presented:
1) D. Neufeld, GRF and C. McKee, Ap J 2018: Hadronically interacting DM in the mass range 0.6-6 GeV forms a calculable atmosphere around the Earth, leading to novel constraints.
2) D. Wadekar and GRF, 2019: Millicharge and hadronic interactions of DM and gas is strongly constrained at velocities ~10 km/s by the Leo T dwarf galaxy, and for velocities ~ 200 km/s by Mikly Way clouds.
The > 10-sigma deficit between the observed abundance of primordial 7Li relative to the prediction of standard BBN can be explained by sexaquark interactions, but the scenario produces tensions with the NFM18 limits. How these tensions might be circumvented will be discussed; related mechanisms to explain the 7Li puzzle without relying on the S will be mentioned. (GRF, R. Galvez and X. Xu, in preparation)
A stable sexaquark is surprisingly elusive and experimental strategies for discovering it in the lab can be discussed, time permitting. For instance, the recent BABAR search in exclusive final states would need a factor ~10^4 higher statistics to be sensitive. The high degree of symmetry in the sexaquark wavefunction suppresses many decay/fusion channels, invalidating naive estimates of the allowed mass range (Z. Wang and GRF, in preparation)