This thesis presents an exclusive measurement of the branching fraction B for the rare charmless hadronic B decays to ?K final states. A sample of 22.57±0.36 million BB pairs was collected with the BaBar detector at the Stanford Linear Accelerator Center's PEP-II B Factory, during the Run 1 data taking period (1999-2000).

Measurements of the branching fractions (average over charge-conjugate decays), B, and CP violating asymmetries, ACP, of the decays B± → K*±?0 and B± → ?±?0 are presented.

Over the last few years, the B factories have established the Cabbibo-Kobayashi-Maskawa mechanism of CP violation in the Standard Model through the study of the decays of B mesons. The focus of Belle and BaBar has now expanded to the search for signatures of new physics beyond the Standard Model, particularly through examination of flavor-changing neutral-current transitions, which proceed through diagrams involving virtual loops. These decays are suppressed in the Standard Model, increasing sensitivity to new-physics effects but decreasing branching fractions. Exploiting large and growing datasets, BaBar and Belle have made many measurements in loop decays where a b quark transitions to an s quark, observing hints of possible deviations from Standard Model expectations in CP-violating measurements.

The BABAR Collaboration is a high energy physics experiment located at the Stanford Linear Accelerator Center. The primary goal of the experiment is to study charge and parity violation in the B-meson sector, however the copious production of B mesons decaying to other final states allows for a wide-ranging physics program. In particular, one can access the charmonium system via colour-suppressed b → c decays of the type B → c$ar{c}$K. This thesis presents a study of B →c$ar{c}$?K decays where c$ar{c}$ includes J/? and ?(2S), and K includes K±, KS0 and K*(892). The particular emphasis is on a search for the radiative decays X(3872) → J/?? and X(3872) → ?(2S)?. The X(3872) state is a recently-discovered resonance of undetermined quark composition, speculatively a conventional charmonium state or exotic four-quark di-meson molecule. This research is also sensitive to the well-known radiative charmonium decays B → ?c1,2K, which are used as verification for the analysis technique. This dissertation sets the best B → ?c1K branching fraction measurements to date, and sees the first evidence for factorization-suppressed B0 → ?c2}K*0 decay at a level of 3.6?. It also provides evidence for X(3872) → J/?? and X(3872) → ?(2S)? with 3.6? and 3.3? significance, respectively. The product of branching fractions ?(B± → X(3872)K±) • ?(X(3872) → J/??) = (2.8 ± 0.8(stat.) ± 0.2(syst.)) x 10−6 and ?(B{± → X(3872)K±) → ?(X(3872) → ?(2S)?) = (9.5 ± 2.7(stat.) ± 0.9(syst.)) x 10-6 are measured. These results improve upon previous X(3872) → J/?? measurements, and represent the first evidence for X(3872) → ?(2S)?.

In a sample of 471×106 BB¯ events collected with the BABAR detector at the PEP-II e+e- collider we study the rare decays B→K(*)l+l-, where l+l- is either e+e- or ?+?-. We report results on partial branching fractions and isospin asymmetries in seven bins of dilepton mass-squared. We further present CP and lepton-flavor asymmetries for dilepton masses below and above the J/? resonance. We find no evidence for CP or lepton-flavor violation. The partial branching fractions and isospin asymmetries are consistent with the Standard Model predictions and with results from other experiments.