Weak Decays of Heavy-Light Mesons on the Lattice: Semi-Leptonic Formfactors

We report results (on an intermediate statistics sample) of a study of weak semi-leptonic formfactors of $B$ and $D$ decays, addressing the uncertainties from mass extrapolations to chiral and to heavy quarks. Moreover, we present a nonperturbative test to the LMK current renormalization scheme for vector current {\it transition} matrix elements and find remarkable agreement.Comment: 13 pages, uuencoded, updated table

Semileptonic Decays of D and B Mesons

We report results of our ongoing investigation concerning semileptonic decays of heavy pseudoscalar mesons into pseudoscalar and vector mesons. Particular attention is paid to uncertainties in the $q^2$ and the heavy quark mass dependence of formfactors. Moreover we present a non-perturbative test to the LMK current renormalization scheme for vector current transition matrix elements and find remarkable agreement.Comment: 3 pages, uuencoded, contribution to Lat 9

Beautiful Baryons from Lattice QCD

We perform a lattice study of heavy baryons, containing one ($\Lambda_b$) or two $b$-quarks ($\Xi_b$). Using the quenched approximation we obtain for the mass of $\Lambda_b$ $$M_{\Lambda_b}= 5.728 \pm 0.144 \pm 0.018 {\rm GeV}.$$ The mass splitting between the $\Lambda_b$ and the B-meson is found to increase by about 20\% if the light quark mass is varied from the chiral limit to the strange quark mass.Comment: 11 pages, Figures obtained upon request from [email protected]

Semileptonic Decays of Heavy Mesons: A Status Report

We present intermediate results on our ongoing investigation concerning semileptonic decays of heavy pseudoscalar mesons into pseudoscalar and vector mesons. The corresponding formfactors are evaluated at several momenta and appropriate combinations of four light and four heavy quarks, which are chosen to allow for an extrapolation into the B Meson region. In order to obtain clear groundstate signals we apply gauge invariant ``Wuppertal'' smearing to the quarks. The analysis is based on 32 quenched gauge configurations of size $24^3 \times 64$ at $\beta=6.3$, with Wilson fermions.Comment: 3 pages, uuencoded, contribution to Lat 9

Coarsening Dynamics of Crystalline Thin Films

The formation of pyramid-like structures in thin-film growth on substrates with a quadratic symmetry, e.g., {001} surfaces, is shown to exhibit anisotropic scaling as there exist two length scales with different time dependences. Analytical and numerical results indicate that for most realizations coarsening of mounds is described by an exponent n=0.2357. However, depending on material parameters, n may lie between 0 (logarithmic coarsening) and 1/3. In contrast, growth on substrates with triangular symmetries ({111} surfaces) is dominated by a single length scale and an exponent n=1/3.Comment: RevTeX, 4 pages, 3 figure

Light Spectrum and Decay Constants in Full QCD with Wilson Fermions

We present results from an analysis of the light spectrum and the decay constants f_{\pi} and f_V^{-1} in Full QCD with n_f=2 Wilson fermions at a coupling of beta=5.6 on a 16^3x32 lattice.Comment: 3 pages, LaTeX with 4 eps figures, Talk presented at LATTICE96(spectrum

Heat and groundwater transport between the Antarctic Ice Sheet and subglacial sedimentary basins from electromagnetic geophysical measurements

Numerical models of contemporary as well as paleo-ice sheets suggest that groundwater and heat exchanges between subglacial sedimentary basins and the ice sheet above, can be substantial and influence the flow of ice above. So far, an approach for the measurement and assessment of such heat fluxes has not been available. Here, we summarise existing evidence for groundwater and heat exchanges between contemporary and paleo ice sheets and the substrate below. We then explain the utility of electromagnetic geophysical measurements in elucidating such exchanges, and present magnetotelluric synthetic models of the deep sedimentary basin beneath the Institute Ice Stream in West Antarctica by way of illustration. Finally, we propose a simple empirical model by which heat exchanges between subglacial sedimentary basins and the overlying ice sheet can be estimated to first-order from electromagnetic data

Strong Resonance of Light in a Cantor Set

The propagation of an electromagnetic wave in a one-dimensional fractal object, the Cantor set, is studied. The transfer matrix of the wave amplitude is formulated and its renormalization transformation is analyzed. The focus is on resonant states in the Cantor set. In Cantor sets of higher generations, some of the resonant states closely approach the real axis of the wave number, leaving between them a wide region free of resonant states. As a result, wide regions of nearly total reflection appear with sharp peaks of the transmission coefficient beside them. It is also revealed that the electromagnetic wave is strongly enhanced and localized in the cavity of the Cantor set near the resonant frequency. The enhancement factor of the wave amplitude at the resonant frequency is approximately $6/|\eta_\mathrm{r}|$, where $\eta_\mathrm{r}$ is the imaginary part of the corresponding resonant eigenvalue. For example, a resonant state of the lifetime $\tau_\mathrm{r}=4.3$ms and of the enhancement factor $M=7.8\times10^7$ is found at the resonant frequency $\omega_\mathrm{r}=367$GHz for the Cantor set of the fourth generation of length L=10cm made of a medium of the dielectric constant $\epsilon=10$.Comment: 20 pages, 11 figures, to be published in Journal of the Physical Society of Japa

Scaling Study of the Leptonic Decay Constants of Heavy-Light Mesons: A Consumers Report on Improvement Factors

A high statistics calculation, performed at $\beta =5.74,\;6.00$ and $6.26$, enables us to study the variation of the leptonic decay constants $f_P$ of heavy pseudoscalar mesons with the lattice spacing $a$. We observe only a weak $a$ dependence when the standard $\sqrt{2\kappa}$ normalization is used for the quark fields, whereas application of the Kronfeld-Mackenzie normalization induces a stronger variation with $a$. Increasing the meson mass from $1.1GeV$ to $2.3GeV$ this situation becomes even more pronounced.Comment: Lattice 93, 3 pages Latex, 2 postscript figures (epsf style