Penguin Mediated B Decays at BaBar

The authors report on preliminary results of searches for penguin mediated B decays based on 20.7 fb-1 of data collected at the Υ(4S) peak with the BABAR detector at PEP-II. The following branching fractions have been measured: Β(B+ → φK+) = (7.7-1.4+1.6 ± 0.8) x 10-6, Β(B0 → φK0) = (8.1-2.5+3.1 ± 0.8) x 10-6, Β(B+ → φK*+) = (9.7-3.4+4.2 ± 1.7) x 10-6, Β(B0 → φK*0) = (8.7-2.1+2.5 ± 1.1) x 10-6, Β(B+ → ωπ+) = (6.6-1.8+2.1 ± 0.7) x 10-6, Β(B → ηK*0) = (19.8-5.6+6.5 ± 1.7) x 10-6, where the first error is statistical and the second systematic. For several other modes they report upper limits on their branching fractions; for example for the following flavor-changing neutral current decays, Β(B → Kl+l-) < 0.6 x 10-6, Β(B → K*l+l-) < 2.5 x 10-6, at 90% Confidence Level (C.L.)