Source of CP Violation for Baryon Asymmetry of the Universe

The baryon asymmetry of the Universe requires CP violation, but the Standard Model falls short by a factor of ${10}^{-10}$ or more. Starting from a clue at the $B$ factories, we point out that the large Yukawa couplings of the sequential fourth generation $t^{\mathrm{\prime }}$ and $b^{\mathrm{\prime }}$ quarks can provide enhancement by a factor of over ${10}^{13}$, making the 2-3-4 generation quark sector a viable source of CP violation for the baryon asymmetry of the Universe. With recent hints of large $\sin 2{\mathrm{\Phi }}_{B_s}$ in $B_s^0$-${\bar{B}}_s^0$ mixing from the Tevatron, the ultimate test would be to discover the $t^{\mathrm{\prime }}$ and $b^{\mathrm{\prime }}$ quarks at the Large Hadron Collider.