Non-Leptonic B Decays into K-Resonances

We estimate the non-leptonic B decays $B \rightarrow (\psi ,\psi^\prime , \chi_{1c})+K^i$, where $K^i$ are various K-meson resonances. We use the model of Isgur, Wise, Scora and Grinstein in the context of heavy quark effective theory, to calculate the hadronic matrix elements. Our estimates show that a substantial fraction of $B \rightarrow X_s \psi$ results in higher resonances of K-meson and besides $B \rightarrow K(K^*) \psi$, a considerable fraction of $B \rightarrow X_s (c\bar c)$ goes to $B \rightarrow (K,K^*)+( \psi^{\prime},\chi_{1c})$.Comment: 9 pages, late

CLEO-c hot topics

Selected recent results and future prospects for the CLEO-c experiment at CESR are reviewed. The topics covered include measurements of leptonic and semileptonic charm decays made with data collected at the ψ(3770) resonance and results from a scan of the center-of-mass energy range from 3970 to 4260 MeV addressing the details of open-charm production and properties of the Y (4260) state observed last year by BaBar

Reliability Testing of AlGaN/GaN HEMTs Under Multiple Stressors

We performed an experiment on AlGaN/GaN HEMTs with high voltage and high power as stressors. We found that devices tested under high power generally degraded more than those tested under high voltage. In particular, the high-voltage-tested devices did not degrade significantly as suggested by some papers in the literature. The same papers in the literature also suggest that high voltages cause cracks and pits. However, the high-voltage-tested devices in this study do not exhibit cracks or pits in TEM images, while the high-power-tested devices exhibit pits

Synthesis and Characterization of Amorphous Hydrated Alkali Thio-Hydroxogermanates

The synthesis, structure, and nonhumidified proton conductivity of the hydrated alkali thio-hydroxogermanates, denoted as MxGeSx(OH)4-x·yH2O (1 ≤ x ≤ 4, 0 \u3c y \u3c 8) for M = Na, K, Rb, and Cs, are reported. These materials are generally X-ray amorphous when produced by a low-temperature (75 °C) aqueous solution evaporation−precipitation route. Raman and IR spectroscopies indicate mixed chalcogenide germanium central anions with distinct asymmetric Ge−O and symmetric Ge−S stretching modes observable around 820−754 and 500−325 cm-1, respectively. These thio-oxoanions possess a combination of thermally stable hydroxyl groups and hydrophilic alkali associated with the nonbridging sulfurs. Alternating current impendence measurements performed under anhydrous conditions on low-pressure sealed pellets reveal fast ionic conductivity, 10-3−10-2 S/cm, for typical temperatures between 100 and 275 °C. The observed falloff in conductivity at higher temperatures is consistent with the appearance of endothermic transitions in differential scanning calorimetry measurements of hermetically sealed samples, presumably from the “boiling” or sublimation of a crystalline water sublattice. Corresponding onset temperatures were observed between 150 and 275 °C and dependent on the alkali and composition. Under dry atmosphere conditions, thermogravimetric analysis mass loss measurements indicate continuous mass loss above the preparation temperature of 75 °C

Analytical approximation for the sphere-sphere Coulomb potential

A simple analytical expression, which closely approximates the Coulomb potential between two uniformly charged spheres, is presented. This expression can be used in the optical potential semiclassical analyses which require that the interaction be analytic on and near the real r-axis.Comment: 4 pages including 3 figures and 1 tabl

Numerical framework for transcritical real-fluid reacting flow simulations using the flamelet progress variable approach

An extension to the classical FPV model is developed for transcritical real-fluid combustion simulations in the context of finite volume, fully compressible, explicit solvers. A double-flux model is developed for transcritical flows to eliminate the spurious pressure oscillations. A hybrid scheme with entropy-stable flux correction is formulated to robustly represent large density ratios. The thermodynamics for ideal-gas values is modeled by a linearized specific heat ratio model. Parameters needed for the cubic EoS are pre-tabulated for the evaluation of departure functions and a quadratic expression is used to recover the attraction parameter. The novelty of the proposed approach lies in the ability to account for pressure and temperature variations from the baseline table. Cryogenic LOX/GH2 mixing and reacting cases are performed to demonstrate the capability of the proposed approach in multidimensional simulations. The proposed combustion model and numerical schemes are directly applicable for LES simulations of real applications under transcritical conditions.Comment: 55th AIAA Aerospace Sciences Meeting, Dallas, T