6-quark Dark Matter
  It has recently been proposed that the relatively inert, highly symmetric,
neutral flavor singlet scalar hadron made of uuddss quarks may have a mass < 2
(m_p + m_e). This is consistent with QCD theory, and with existing accelerator
and non-accelerator constraints. For mass in the 1.5-1.8 GeV range, the
observed DM relic abundance and the observed DM to ordinary matter ratio can
emerge naturally. Dark matter freezes out before primordial nucleosynthesis and
does not significantly impact primordial abundances, so the conventional
argument that DM is non-baryonic does not apply. The interaction cross section
between DM and the gas in the Galaxy is such that the dark matter in our local
neighborhood is naturally co-rotating with the solar system, to a sufficient
degree that DM may not have enough energy to be detected in applicable DM
experiments. Interaction with the gas in galactic disks provides the first
(non-MONDian) explanation for the striking correlation in the small-scale
structure of rotation curves and the inhomogeneous distribution of gas, and
also accounts (unlike MOND) for instances of galaxies not exhibiting such
correlations. Depending on the cross-section, a DM-baryon interaction can
produce a dark matter disk as suggested by recent studies, and has many or all
virtues of self-interacting DM (SIDM) for removing inconsistencies of LCDM. Lab
experiments to discover this particle are discussed.
