Study of the B^0 Semileptonic Decay Spectrum at the Upsilon(4S) Resonance

We have made a first measurement of the lepton momentum spectrum in a sample of events enriched in neutral B's through a partial reconstruction of B0 --> D*- l+ nu. This spectrum, measured with 2.38 fb**-1 of data collected at the Upsilon(4S) resonance by the CLEO II detector, is compared directly to the inclusive lepton spectrum from all Upsilon(4S) events in the same data set. These two spectra are consistent with having the same shape above 1.5 GeV/c. From the two spectra and two other CLEO measurements, we obtain the B0 and B+ semileptonic branching fractions, b0 and b+, their ratio, and the production ratio f+-/f00 of B+ and B0 pairs at the Upsilon(4S). We report b+/b0=0.950 (+0.117-0.080) +- 0.091, b0 = (10.78 +- 0.60 +- 0.69)%, and b+ = (10.25 +- 0.57 +- 0.65)%. b+/b0 is equivalent to the ratio of charged to neutral B lifetimes, tau+/tau0.Comment: 14 page, postscript file also available at http://w4.lns.cornell.edu/public/CLN

Observation of the Ξc+\Xi_c^+ Charmed Baryon Decays to Σ+K−π+\Sigma^+ K^-\pi^+, Σ+Kˉ∗0\Sigma^+ \bar{K}^{*0}, and ΛK−π+π+\Lambda K^-\pi^+\pi^+

We have observed two new decay modes of the charmed baryon $\Xi_c^+$ into $\Sigma^+ K^-\pi^+$ and $\Sigma^+ \bar{K}^{*0}$ using data collected with the CLEO II detector. We also present the first measurement of the branching fraction for the previously observed decay mode $\Xi_c^+\to\Lambda K^-\pi^+\pi^+$. The branching fractions for these three modes relative to $\Xi_c^+\to\Xi^-\pi^+\pi^+$ are measured to be $1.18 \pm 0.26 \pm 0.17$, $0.92 \pm 0.27 \pm 0.14$, and $0.58 \pm 0.16 \pm 0.07$, respectively.Comment: 12 page uuencoded postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

Radiative Decay Modes of the D0D^{0} Meson

Using data recorded by the CLEO-II detector at CESR we have searched for four radiative decay modes of the $D^0$ meson: $D^0\to\phi\gamma$, $D^0\to\omega\gamma$, $D^0\to\bar{K}^{*}\gamma$, and $D^0\to\rho^0\gamma$. We obtain 90% CL upper limits on the branching ratios of these modes of $1.9\times 10^{-4}$, $2.4\times 10^{-4}$, $7.6\times 10^{-4}$ and $2.4\times 10^{-4}$ respectively.Comment: 15 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

Measurement of the Mass Splittings between the bbˉχb,J(1P)b\bar{b}\chi_{b,J}(1P) States

We present new measurements of photon energies and branching fractions for the radiative transitions: Upsilon(2S)->gamma+chi_b(J=0,1,2). The masses of the chi_b states are determined from the measured radiative photon energies. The ratio of mass splittings between the chi_b substates, r==(M[J=2]-M[J=1])/(M[J=1]-M[J=0]) with M the chi_b mass, provides information on the nature of the bbbar confining potential. We find r(1P)=0.54+/-0.02+/-0.02. This value is in conflict with the previous world average, but more consistent with the theoretical expectation that r(1P)<r(2P); i.e., that this mass splittings ratio is smaller for the chi_b(1P) triplet than for the chi_b(2P) triplet.Comment: 11 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

Studies of the Cabbibo-Suppressed Decays D+→π0ℓ+νD^+ \to \pi^0 \ell^+ \nu and D+→ηe+νeD^+ \to \eta e^+ \nu_e

Using 4.8 fb$^{-1}$ of data taken with the CLEO II detector, the branching fraction for the Cabibbo-suppressed decay $D^+\to\pi^0\ell^+\nu$ measured relative to the Cabibbo favored decay $D^+\to\bar{K^0}\ell^+\nu$ is found to be $0.046\pm 0.014\pm 0.017$. Using $V_{cs}$ and $V_{cd}$ from unitarity constraints, we determine $| f_+^{\pi}(0)/f_+^K(0)|^2=0.9\pm 0.3\pm 0.3$ We also present a 90% confidence level upper limit for the branching ratio of the decay $D^+ \to \eta e^+\nu_e$ relative to that for $D^+ \to \pi^0 e^+\nu_e$ of 1.5.Comment: 10 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

Refractive index dispersion of gallium lanthanum sulfide and oxysulfide glasses

Gallium lanthanum sulfide-based glasses are attractive for new laser and nonlinear optical applications at near Infrared region. Refractive indexes were measured for Ga2As3-La2S3 and Ga2S3-La2O3 glasses in the range of 0.5 and 1.7µm using the minimum deviation method. Data is analysed by Wemple and Didomenico equation. These glasses have relatively large average electronic bandgaps E in comparison with other chalcogenide glasses. Possible origins of these features are discussed

Propagação de pteridófitas in vitro e in vivo através de esporos Fern propagation in vitro and in vivo from spores

Sujeitas ao processo de extinção, em decorrência do extrativismo, as samambaias arbóreas Dicksonia sellowana (Presl.) Hook e Cyathea schanschin Mart, das quais se obtémo xaxim, são espécies ainda pouco estudadas quanto à propagação. Com o objetivo de desenvolver um método adequado à propagação destas espécies, através de esporos, realizaram-se experimentos in vitro e in vivo. Para a desinfecção dos esporos, utilizaram-se soluções de hipoclorito de cálcio, em diferentes concentrações, ou de sódio, comparando-se sua eficiência. Para o cultivo in vitro, empregaram-se os meios nutritivos de Murashige e Skoog modificado e de Jones e a solução de Knop modificada. Na cultura in vivo utilizaram-se xaxim, estagno, terriço ou tijolo fragmentado. Como condições de cultivo, manteve-se a temperatura a 25 &plusmn;1&deg;C e o fotoperíodo de 16 horas. Apesar da elevada contaminação durante o processo de germinação in vitro e in vivo, a desinfecção com hipoclorito de cálcio a 2% foi mais eficiente. Os esporos germinaram em 4 a 8 semanas e os prótalos formaram-se após 30 a 40 dias. Obteve-se maior percentagem de germinação e formação de prótalos com os meios de Jones e Knop, bem como xaxim e esfagno, e a germinação de esporos ocorreu mais rapidamente na ausência de esporângios.<br>The objective of this experiment was to study the fern propagation from spores of Cyathea schanschin Mart and Dicksonia sellowiana (Presl.) Hook. The spores were decontaminated in calcium or sodium hypochlorite solutions. The in vitro experiments were performed with the media: MS modified, Jones or Knop's solution modified. Tree-fern fibre, sphagnum moss, loam soil or brick peaces were, used for the in vivo experiments. The temperature was mantained at 25 &plusmn; 1&deg;C and 16 hours of photoperiod for both treatments (In vivo and in vitro cultures). Besides the high percentage of contamination during the germination process, in vitro and in vivo, the best results were obtained with decontamination made in a 2% sodium hypochlorite solution. The spores germination occurred after a period of 4 to 8 weeks and the prothalli were formed 30 to 40 days latter. There was a high percentage of germination and prothalli formation in Jones and Knop media, and tree-fern fibre and sphagnum moss substrates