Search for the Decays B0_(s) --> e+ mu- and B0_(s) --> e+ e- in CDF Run II

We report results from a search for the lepton flavor violating decays B0(s) --> e+ mu- and B0 --> e- mu-, and the flavor-changing neutral-current decays B0(s) --> e+ e- and B0 --> e+ e-. The analysis uses data corresponding to 2 fb-1 of integrated luminosity of p anti-p collisions at s**(1/2) =1.96 TeV collected with the upgraded Collider Detector (CDF II) at the Fermilab Tevatron. The observed number of B0 and B0(s) candidates is consistent with background expectations. The resulting Bayesian upper limits on the branching ratios at 90% credibility level are B(B0(s) --> e+ mu-) < 2.0 x 10-7, B(B0 --> e+ mu-) < 6.4 x 10-8, B(B0(s) --> e+ e-) < 2.8 x 10-7, and B(B0 --> e+ e-) < 8.3 x 10-8. From the limits on B(B0_(s) --> e+ mu-), the following lower bounds on the Patti-Salam leptoquark masses are also derived: M_LQ(B0(s) --> e+ mu-) > 47.8 TeV/c2, and M_LQ(B0 --> e+ mu-) > 59.3 TeV/c3, at 90% credibility level.