S. Nam

Branching fractions of τ Leptons to three charged Hadrons

From electron-positron collision data collected with the CLEO detector operating at Cornell Electron Storage Ring near sqrt[s]=10.6 GeV, improved measurements of the branching fractions for tau decays into three explicitly identified hadrons and a neutrino are presented as B(tau(-)-->pi(-)pi(+)pi(-)nu(tau))=(9.13+/-0.05+/-0.46)%, B(tau(-)-->K-pi(+)pi(-)nu(tau))=(3.84+/-0.14+/-0.38) x 10(-3), B(tau(-)-->K-K+pi(-)nu(tau))=(1.55+/-0.06+/-0.09) x 10(-3), and B(tau(-)-->K-K+K-nu(tau))<3.7 x 10(-5) at 90% C.L., where the uncertainties are statistical and systematic, respectively.

Measurement of exclusive B decays to final states containing a charmed baryon

Using data collected by the CLEO detector in the Upsilon(4S) region, we report new measurements of the exclusive decays of B mesons into final states of the type Lambda_c^+ p-bar n(pi), where n=0,1,2,3. We find signals in modes with one, two and three pions and an upper limit for the two body decay Lambda_c^+ pbar. We also make the first measurements of exclusive decays of B mesons to Sigma_c p-bar n(pi), where n=0,1,2. We find signals in modes with one and two pions and an upper limit for the two body decay Sigma_c p-bar. Measurements of these modes shed light on the mechanisms involved in B decays to baryons.

Search for baryons in the radiative penguin decay b→sγ

We have searched for the baryon-containing radiative penguin decays B^- -> \Lambda p-bar \gamma and B^- -> \Sigma^0 p-bar \gamma, using a sample of 9.7 million BBbar events collected at the \Upsilon(4S) with the CLEO detector. We find no evidence for either, and set 90% confidence level upper limits for photons with B rest frame energy greater than 2.0 GeV of [Br(B^- -> \Lambda p-bar \gamma) + 0.3 Br(B^- -> \Sigma^0 p-bar \gamma)] \Sigma^0 p-bar \gamma) + 0.4 Br(B^- -> \Lambda p-bar \gamma)] < 6.4 x 10^-6. From the latter, we estimate (for photons with B rest frame energy greater than 2.0 GeV) Br(B -> X_s \gamma, X_s containing baryons) s \gamma that are less than half the combined statistical and systematic errors quoted on these quantities.

Measurement of the charge asymmetry in B→K*: (892) ±π∓

We report on a search for a CP-violating asymmetry in the charmless hadronic decay B -> K*(892)+- pi-+, using 9.12 fb^-1 of integrated luminosity produced at \sqrt{s}=10.58 GeV and collected with the CLEO detector. We find A_{CP}(B -> K*(892)+- pi-+) = 0.26+0.33-0.34(stat.)+0.10-0.08(syst.), giving an allowed interval of [-0.31,0.78] at the 90% confidence level.

Search for B→p̄e-ν̄eX decay using a partial reconstruction method

Using data collected on the Upsilon(4S) resonance and the nearby continuum by the CLEO detector at the Cornell Electron Storage Ring, we have searched for the semileptonic decay of B mesons to electron-antiproton inclusive final states. We obtain an upper limit of B(B-> pbar e nuebar X) u decay, we find an upper limit of B(B^- -> p pbar e nuebar)< 5.2e-3. All upper limits are measured at the 90% confidence level.

Cabibbo-suppressed decays of D+ → π+π 0, K+K̄0,K+π0

Using a 13.7 fb-1 data sample collected with the CLEO II and II.V detectors, we report new branching fraction measurements for two Cabibbo-suppressed decay modes of the D+ meson: BR(D+ -> pi+ pi0) = (1.31 +/- 0.17 +/- 0.09 +/- 0.09) x 10^(-3)and BR(D+ -> K+ K0bar) = (5.24 +/- 0.43 +/- 0.20 +/- 0.34) x 10^(-3) which are significant improvements over past measurements. The errors reflect statistical and systematical uncertainties as well as the uncertainty in the absolute D+ branching fraction scale. We also set the first 90% confidence level upper limit on the branching fraction of the doubly Cabibbo-suppressed decay mode BR(D+ -> K+ pi0) < 4.2 x 10^(-4).K. Arms, E. Eckhart, K. K. Gan, C. Gwon, K. Honscheid, R. Kass, H. Severini, P. Skubic, S.A. Dytman, J.A. Mueller, S. Nam, V. Savinov, J. W. Hinson, G. S. Huang, J. Lee, D. H. Miller, V. Pavlunin, B. Sanghi, E. I. Shibata, I. P. J. Shipsey, D. Cronin-Hennessy, C. S. Park, W. Park, J. B. Thayer, E. H. Thorndike, T. E. Coan, Y. S. Gao, F. Liu, R. Stroynowski, M. Artuso, C. Boulahouache, S. Blusk, E. Dambasuren, O. Dorjkhaidav, R. Mountain, H. Muramatsu, R. Nandakumar, T. Skwarnicki, S. Stone, J.C. Wang, A. H. Mahmood, S. E. Csorna, I. Danko, G. Bonvicini, D. Cinabro, M. Dubrovin, A. Bornheim, E. Lipeles, S. P. Pappas, A. Shapiro, W. M. Sun, A. J. Weinstein, R. A. Briere, G. P. Chen, T. Ferguson, G. Tatishvili, H. Vogel, M. E. Watkins, N. E. Adam, J. P. Alexander, K. Berkelman, V. Boisvert, D. G. Cassel, J. E. Duboscq, K. M. Ecklund, R. Ehrlich, R. S. Galik, L. Gibbons, B. Gittelman, S. W. Gray, D. L. Hartill, B. K. Heltsley, L. Hsu, C. D. Jones, J. Kandaswamy, D. L. Kreinick, A. Magerkurth, H. Mahlke-Krüger, T. O. Meyer, N. B. Mistry, J. R. Patterson, T. K. Pedlar, D. Peterson, J. Pivarski, S. J. Richichi, D. Riley, A. J. Sadoff, H. Schwarthoff, M. R. Shepherd, J. G. Thayer, D. Urner, T. Wilksen, A. Warburton, M. Weinberger, S. B. Athar, P. Avery, L. Breva-Newell, V. Potlia, H. Stoeck, J. Yelton, B. I. Eisenstein, G. D. Gollin, I. Karliner, N. Lowrey, C. Plager, C. Sedlack, M. Selen, J. J. Thaler, J. Williams, K. W. Edwards, D. Besson, V. V. Frolov, D. T. Gong, Y. Kubota, S. Z. Li, R. Poling, A. Smith, C. J. Stepaniak, J. Urheim, Z. Metreveli, K.K. Seth, A. Tomaradze, P. Zweber, and J. Ernst