The Effects of Fourth Generation on the Total Branching Ratio and the Lepton Polarization in ${\Lambda }_b\text{rar}\Lambda {\ell }^{+}{\ell }^{-}$ decay

Abstract

This study investigates the influence of the fourth generation quarks on the total branching ratio and the single lepton polarizations in \Lambda_b --> \Lambda \ell^+ \ell^- decay. Taking $|V_{t^{\prime }s}{V}_{t^{\prime }b}|0.01-0.03withphasejustbelow$90^\circ$, which is consistent with the b\to s\ell^+\ell^- rate and the B_s mixing parameter \Delta m_{B_s}, we obtain that the total branching ratio and the single lepton(\mu, \tau) polarizations are quite sensitive to the existence of fourth generation. It can serve as a good tool to search for new physics effects, precisely, to search for the fourth generation quarks(t', b').

Comments: 21 pages, 9 figures