Search for the Decays $B_{(s)}^0\to e^{+}{\mu }^{-}$ and $B_{(s)}^0\to e^{+}{e}^{-}$ in CDF Run II

Abstract

We report results from a search for the lepton flavor violating decays $B_{(s)}^0\to e^{+}{\mu }^{-}$, and the flavor-changing neutral-current decays $B_{(s)}^0\to e^{+}{e}^{-}$. The analysis uses data corresponding to $2f{\mathrm{b}}^{-1}$ of integrated luminosity of $p\bar{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ collected with the upgraded Collider Detector (CDF II) at the Fermilab Tevatron. The observed number of $B_{(s)}^0$ candidates is consistent with background expectations. The resulting Bayesian upper limits on the branching ratios at 90% credibility level are $\mathcal{B}(B_s^0\to e^{+}{\mu }^{-})<2.0\times 10^{-7}$, $\mathcal{B}(B^0\to e^{+}{\mu }^{-})<6.4\times 10^{-8}$, $\mathcal{B}(B_s^0\to e^{+}{\mu }^{-})<2.0\times 10^{-7}$ and $\mathcal{B}(B^0\to e^{+}{\mu }^{-})<6.4\times 10^{-8}$. From the limits on $\mathcal{B}(B_{(s)}^0\to e^{+}{\mu }^{-})$, the following lower bounds on the Pati-Salam leptoquark masses are also derived: $M_{LQ}(B_s^0\to e^{+}{\mu }^{-})>47.8TeV/{\mathrm{c}}^2$, and $M_{LQ}(B^0\to e^{+}{\mu }^{-})>59.3TeV/{\mathrm{c}}^2$, at 90% credibility level.

submitted to PRL