$B_s-{\bar{B}}_s$ Mixing constraints on FCNC and a non-universal $Z^{\prime }$

Abstract

$B_s-{\bar{B}}_s$ mixing has been measured recently by D0 and CDF. The range predicted in the standard model is consistent with data. However, the standard model central values for $\Delta M_{B_s}$ and also $\Delta M_{B_d}$ are away from the data which may be indications of new physics. Using the observed values of $\Delta M_{B_s}$ and $\Delta M_{B_d}$ we study general constraints on flavor changing $Z^{\prime }$ interactions. In models with non-universal $Z^{\prime }$ couplings we find that significant enhancements over the standard model are still possible in the rare decay modes $B\to X_s{\tau }^{+}{\tau }^{-}$, $B\to X_s\nu \bar{\nu }$ and $B_s\to {\tau }^{+}{\tau }^{-}$. Tree level $Z^{\prime }$ contributions to $K\to \pi \nu \bar{\nu }$ are now constrained to be very small, but one loop effects can still enhance the standard model rate by a factor of two.

Comments: 16 pages, 7 figures