| We present a mechanism to generate the baryon asymmetry of the Universe which preserves the net baryon number created in the Big Bang. If dark matter particles carry baryon number BX, and sannihX&d1; < sannihX , the X¯'s freeze out at a higher temperature and have a larger relic density than X's. If m X ≲ 4.5 BX GeV and the annihilation cross sections differ by O (10%) or more, this type of scenario naturally explains the observed O DM ≈ 5 Ob. We present two concrete scenarios, in which the observed values of O DM and Ob are explained. One of them entails an H dibaryon, a particle predicted within QCD. We focus on long-lived H and find that remarkably it appears to evade all experimental constraints (exotic nuclei searches, double hypernuclei experiments), when account is taken of its expected compact spatial function. The other candidate involves a new ∼ 4 GeV particle with dimension-6 couplings to quarks. We analyze the properties these particles should have in order to be valuable dark matter candidates. We further examine whether such properties are in agreement with direct and indirect dark matter constraints---the H dibaryon appears to be ruled out as H¯ dark matter from heat production in Uranus, while the X is safe by many orders of magnitude, but may prove elusive. |
