In an exposure of the SLAC Hybrid Facility (SHF) to a backward scattered laser beam, 136 charm events produced in .gamma.p interactions at 20 GeV have been observed. The SHF 1 m bubble chamber was equipped with a High Resolution Optics camera in order to detect directly the production and decay of charm particles. After imposing rigorous cuts, 48 charged, 50 neutral, and 2 topologically ambiguous decays remain. Using a novel method for estimating the momentum of unconstrained decays, the D meson lifetimes from this sample are measured to be tau/sub D sup +-/ = (8.6 +- 1.3/sub -0.3//sup +0.8/) x 10−13 sec and tau/sub D°/ = (6.1 +- 0.9 +- 0.3) x 10−13 sec with a ratio of R = tau/sub D sup +-/[tau]sub D°/ = (1.4 +- 0.3/sub -0.1//sup +0.2/). This value of R indicates the Spectator Model charm particle decay mechanism is the dominate piece in the D/sub +-/ and D° decay rates. Limits are placed on additional contributions to the D decay rates from other processes including W-Exchange, Final State Interactions, and Pauli Principle Interference. 34 refs., 41 figs.

Results are presented on the use of a high-resolution drift chamber in the Mark II Detector at PEP to measure the lifetimes of D° and D/sup + -/ mesons produced in ee− annihilations at 29 GeV. Based on a sample of 74 events for the D° mesons and 23 events for the D/sup + -/ mesons, the lifetimes are found to be tau/sub D° = 4.7/sub -0.8//sup +0.9/ +- 0.5 x 10−13 s; tau/sub D/sup + -// = 8.9/sub -2.7//sup +3.8/ +- 1.3 x 10−13 s. The ratio of these lifetimes, tau/sub D°//tau/sub D/sup + -// = 1.9/sub -0.7//sup +0.9/ +- 0.3, indicates that the decays of these mesons cannot be explained by the simple spectator model of charmed particle decay.

Data collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC are used to study the lifetimes of the B° and B mesons. The data sample consists of 7.4 fb−1 collected near the Upsilon(4S) resonance. B° and B mesons are fully reconstructed in several exclusive hadronic decay modes to charm and charmonium final states. The B lifetimes are determined from the flight length difference between the two B mesons which are pair-produced in the Upsilon(4S) decay. The preliminary measurements of the lifetimes are tau{sub B0} = 1.506 " 0.052 (stat) " 0.029 (syst) ps, tau{sub B+} = 1.602 " 0.049 (stat) " 0.035 (syst) ps, and of their ratio is tau{sub B+}/tau{sub B0} = 1.065 " 0.044 (stat) " 0.021 (syst).