The authors present measurements of the branching fraction and time-dependent CP-violating asymmetries in B° → K{sub S}°K{sub S}°K{sub S}° decays based on 227 million [Upsilon](4S) → B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. They obtain a branching fraction of (6.9{sub -0.8}{sup +0.9} ± 0.6) x 10−6, and CP asymmetries C = -0.34{sub -0.25}{sup +0.28} ± 0.05 and S = -0.71{sub -0.32}{sup +0.38} ± 0.04, where the first uncertainties are statistical and the second systematic.

Relative branching fractions of B{sub d, s} {yields} h{sup +}h'{sup -} decays (where h, h' = K or {pi}) and direct CP asymmetry in B{sub d} {yields} K{sup +}{pi}{sup -} have been measured with 180 pb{sup -1} of data collected by the CDFII detector at the Tevatron collider. This includes the first BR measurement of a charmless B{sub s} {yields} PP decay (B{sub s} {yields} K{sup +}K{sup -}).

The invariance of physical laws under the combination of exchange of particles with antiparticles (charge conjugation, C) and reversal of coordinates (parity, P) is called CP symmetry. The violation of CP symmetry was first discovered in 1964 in the neutral kaon system, and is in general one of the great puzzles of particle physics. The recent observation of CP violation in the B meson system has been a simultaneous success for model predictions and experiment. The opportunity now exists to probe details of the underlying mechanisms. This thesis presents measurements of the branching fraction and time-dependent CP-violating asymmetry in neutral B decays to J/[psi][pi][sup 0]. The decay amplitude for this channel features both tree and penguin diagram contributions, the interference of which can yield a result for the asymmetry differing from that found in the ''golden mode'' B[sup 0][yields] J/[psi] K[sub s][sup 0]. Using the measured branching fraction and CP asymmetry, constraints are placed on the ratio of penguin to tree amplitudes in B[sup 0][yields] J/[psi][pi][sup 0]. In addition, the impact on the CP asymmetry measurement in B[sup 0][yields] J/[psi] K[sub s][sup 0] is discussed. The results are presented for e[sup+]e[sup -] annihilation data collected with the BABAR detector on the[Upsilon](4S) resonance at the PEP-II asymmetric-energy B Factory at SLAC. The measurement of the branching fraction, based on about 23 million B[bar B] pairs collected between October 1999 and October 2000, yields BF(B[sup 0][yields] J/[psi][pi][sup 0])= (2.0[+-] 0.6 (stat)[+-] 0.2(syst)) x 10[sup -5]. With about 88 million B[bar B] pairs collected during the years 1999-2002, our results for the coefficients of the cosine and sine terms of the CP asymmetry are C[sub J/[psi][pi][sup 0]]= 0.38[+-] 0.41 (stat)[+-] 0.09 (syst) and S[sub J/[psi][pi][sup 0]]= 0.05[+-] 0.49 (stat)[+-] 0.16 (syst).