No abstract

We have observed the decays B° -» K*(892)°j and B~ -> K*(892)~ry, which are evidence for the quark-level process b -• 57. The average branching fraction is (4.5 ± 1.5 ± 0.9) x 10~5. This value is consistent with standard model predictions from electromagnetic penguin diagrams. PACS numbers: 13.40.Hq, 14.40.Jz One-loop, flavor-changing neutral current diagrams, meson decays [1]. They were later identified as a possible known as penguins, were originally introduced into the source of direct CP violation in kaon decay, and hence as theory of weak decays to explain the AI = \ rule in K a contribution to e! /e [2]. Their importance in B meson 674 0031 -9007/93/71 (5)/674(5)$06.00

Using the entire CLEO-c c ð3770Þ ! D " D event sample, corresponding to an integrated luminosity of 818 pb À1 and approximately 5:4 Â 10 6 D " D events, we present a study of the decays D 0 ! À e þ e , D 0 ! K À e þ e , D þ ! 0 e þ e , and D þ ! " K 0 e þ e . Via a tagged analysis technique, in which one D is fully reconstructed in a hadronic mode, partial rates for semileptonic decays by the other D are measured in several q 2 bins. We fit these rates using several form factor parametrizations and report the results, including form factor shape parameters and the branching fractions BðD 0 ! À e þ e Þ ¼ ð0:288 AE 0:008 AE 0:003Þ%, BðD 0 ! K À e þ e Þ ¼ ð3:50 AE 0:03 AE 0:04Þ%, BðD þ ! 0 e þ e Þ ¼ ð0:405 AE 0:016 AE 0:009Þ%, and BðD þ ! "K 0 e þ e Þ ¼ ð8:83 AE 0:10 AE 0:20Þ%, where the first uncertainties are statistical and the second are systematic. Taking input from lattice quantum chromodynamics, we also find jV cd j ¼ 0:234 AE 0:007 AE 0:002 AE 0:025 and jV cs j ¼ 0:985 AE 0:009 AE 0:006 AE 0:103, where the third uncertainties are from lattice quantum chromodynamics.

Using 13.5 fb Ϫ1 of e ϩ e Ϫ annihilation data collected with the CLEO II detector, we have observed a narrow resonance decaying to D s * ϩ 0 with a mass near 2.46 GeV/c 2. The search for such a state was motivated by the recent discovery by the BaBar Collaboration of a narrow state at 2.32 GeV/c 2 , the D sJ * (2317) ϩ , that decays to D s ϩ 0. Reconstructing the D s ϩ 0 and D s * ϩ 0 final states in CLEO data, we observe peaks in both of the corresponding reconstructed mass difference distributions, ⌬M (D s 0)ϭM (D s 0)ϪM (D s) and ⌬M (D s * 0)ϭM (D s * 0)ϪM (D s *), both of them at values near 350 MeV/c 2. We interpret these peaks as signatures of two distinct states, the D sJ * (2317) ϩ plus a new state, designated as the D sJ (2463) ϩ. Because of the similar ⌬M values, each of these states represents a source of background for the other if photons are lost, ignored or added. A quantitative accounting of these reflections confirms that both states exist. We have measured the mean mass differences ͗⌬M (D s 0)͘ϭ350.0Ϯ1.2 (stat)Ϯ1.0 (syst) MeV/c 2 for the D sJ * (2317) ϩ state, and ͗⌬M (D s * 0)͘ϭ351.2Ϯ1.7 (stat)Ϯ1.0 (syst) MeV/c 2 for the new D sJ (2463) ϩ state. We have also searched, but find no evidence, for decays of the two states via the channels D s * ϩ ␥, D s ϩ ␥, and D s ϩ ϩ Ϫ. The observations of the two states at 2.32 and 2.46 GeV/c 2 , in the D s ϩ 0 and D s * ϩ 0 decay channels, respectively, are consistent with their interpretations as cs mesons with an orbital angular momentum Lϭ1 and spin and parity J P ϭ0 ϩ and 1 ϩ .

CLEO has studied B decays to the nal states ` , ` , and !` , wherè = e or. We fully reconstruct these modes using a measurement of the missing energy and momentum in each event to infer the neutrino momentum. With the B 0 and B + modes combined according to isospin predictions for the relative partial widths, we obtain B(B 0 ! ?`+) = (1:8 0:4 0:3 0:2) 10 ?4 and B(B 0 ! ?`+) = (2:5 0:4 +0:5 ?0:7 0:5) 10 ?4 , where the errors are statistical, systematic and the estimated model-dependence. We also estimate jV ub j = (3:3 0:2 +0:3 ?0:4 0:7) 10 ?3 .