Direct CP Violation in b to s Gamma Decays

This dissertation describes a measurement of the direct CP asymmetry between inclusive b → sγ and (bar b) → (bar s)γ decays. This asymmetry is expected to be less than 0.01 in the Standard Model, but could be enhanced up to the order of 0.10 by non-Standard Model contributions. We use a sample of 89 million B(bar B) pairs recorded with the BABAR detector at PEP-II, from which we reconstruct a set of 12 exclusive b → sγ final states containing one charged or neutral kaon and one to three pions. We measure an asymmetry of ACP (b → sγ) = 0.025 ± 0.050(stat.) ± 0.015(syst.), corresponding to an allowed range of -0.06 < ACP (b → sγ) < +0.11 at 90% confidence level