Dark Matter and the Baryon Asymmetry of the Universe

Abstract

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 $B_X$, and ${\sigma }_{\bar{X}}^{\mathrm{annih}}<{\sigma }_X^{\mathrm{annih}}$, the $\bar{X}$'s freeze out at a higher temperature and have a larger relic density than $X$'s. If $m_X \lsi 4.5 B_X $GeV and the annihilation cross sections differ by $\gsi 10%$, this type of scenario naturally explains the observed ${\Omega }_{DM}\approx 5{\Omega }_b$.

4 pp. Added references and corrected typos