We study the two-body decays of B+/- mesons to K+/- and a charmonium state X(cc) in a sample of 210.5 fb(-1) of data from the BABAR experiment. We perform measurements of absolute branching fractions beta(B+/- --> K+/-X(cc)) using a missing mass technique, and report several new or improved results. In particular, the upper limit beta(B+/- --> K+/- X(3872)) < 3.2 x 10(-4) at 90% C.L. and the inferred lower limit beta(X(3872)J/psipi+ pi-) > 4.2% will help in understanding the nature of the recently discovered X(3872).

We measure the B 0 lifetime B 0 and the B 0 -B 0 oscillation frequency ⌬m d with a sample of approximately 14000 exclusively reconstructed B 0 →D* Ϫ ᐉ ϩ ᐉ signal events, selected from 23 million BB pairs recorded at the ⌼(4S) resonance with the BABAR detector at the Stanford Linear Accelerator Center. The decay position of the other B is determined with the remaining tracks in the event, and its b-quark flavor at the time of decay is determined with a tagging algorithm that exploits the correlation between the flavor of the b quark and the charges of its decay products. The lifetime and oscillation frequencies are measured simultaneously with an unbinned maximum-likelihood fit that uses, for each event, the measured difference in decay times of the two B mesons (⌬t), the calculated uncertainty on ⌬t, the signal and background probabilities, and b-quark tagging information for the other B. The results are B 0ϭ (1.523 Ϫ0.023 ϩ0.024 Ϯ0.022) ps and ⌬m d ϭ(0.492Ϯ0.018 Ϯ0.013) ps Ϫ1 . The statistical correlation coefficient between B 0 and ⌬m d is Ϫ0.22.

Di\ Has kin's current view of this event favors the interpretation of it as a rare statistical fluctuation in a conventional photon shower initiated in the very thin aluminum case around the emulsion. We are grateful to him for a conversation about it. 7 Such a bound pole pair would not cause observable ionization as long as the separation is much smaller than 5x lO^1 1 cm. Moreover, unless the pole rest mass greatly exceeds 100 BeV, for y ~ 10 5 the distance travelled before annihilation would be less than a micron. 8 We note that it is characteristic of electron-positron production by y rays that their relative kinetic energy is usually of order m e c 2 . If the pole pairs produced by this same process have a relative kinetic energy Mc 2 , then the strong photon emission which accompanies them would be particularly effective in reducing the relative velocity below that needed to escape. 9 fti a perturbation-theory estimate which neglects pole structure, radiation damping, and final-state enhancement, the ratio of pole-pair production cross section to that for e~~-e + is (g 2 /e 2 ) 2 (m e /m) 2 , which is indeed of order unity for M~ (g 2 /fic)m 1T o However, there is obviously no reason to consider perturbation theory as a guide since g 2 /Uc » 1, and in fact it gives a cross section, near threshold, for pole-antipole production in a two-photon collision which greatly exceeds the unitarity limit. 10 The energetic photons from annihilation of bound pole pairs would result in anomalous extensive air showers without any appreciable muon or other penetrating component.The cross section for yp-+ 7r""A ++ (1236), measured at 5, 8, 11, and 16 GeV from nearzero momentum transfer to -1 GeV 2 (-2 GeV 2 at 16 GeV), rises from small t to a maximum near -4-m 1^i then falls as e^ out to -t ~ 0.2 GeV 2 , after which it becomes roughly equal in slope and magnitude to the single ir + photoproduction cross section (e^). At fixed t, the cross section varies as k~~2, where k is the laboratory photon energy. The results do not agree well with the simple vector-dominance model. The differential cross section for yp-TtA ++ (1236) (1) has been measured at 5, 8, 11, and 16 GeV using the Standard Linear Accelerator Center 20-GeV/ c spectrometer system. 1 This work extends previous measurements in the few-GeV region. 2 The apparatus and method are the same as used by Boyarski et al., 3 with two modifications. First, in addition to the Cerenkov monitor, a secondary-emission quantameter was used to monitor the beam. Except for laboratory angles <1°, these two monitors could be used simultaneously and provided a cross check of the monitor stability; in general, this stability was found to be about ±i%. These monitors were calibrated against two precision calorimeters which served as absolute standards. The second change was the use of a threshold gas Cerenkov counter to separate the group e, II,TT from K mesons and protons. As before, the pions were then identi-fied by their interaction properties.To determine the A ++ yield, the 20-GeV/...