Matrix Elements of Four-quark Operators Relevant to Lifetime Difference \Delta \Gamma_{B_s} from QCD Sum Rules

We extract the matrix elements of four quark operators O_{L,S} relevant to the B_s and \bar B_s life time difference from QCD sum rules. We find the vacuum saturation approximation works reasonably well, i.e., within 10%. We discuss the implications of our results and compare them with the recent lattice QCD determination.Comment: 11 pages, 4 eps figures, Latex. Some reference renewe

X(1835): A Natural Candidate of η′\eta^\prime's Second Radial Excitation

Recently BES collaboration observed one interesting resonance X(1835). We point out that its mass, total width, production rate and decay pattern favor its assignment as the second radial excitation of $\eta^\prime$ meson very naturally

Tropical cyclone rainbands can trigger meteotsunamis

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Shi, L., Olabarrieta, M., Nolan, D. S., & Warner, J. C. Tropical cyclone rainbands can trigger meteotsunamis. Nature Communications, 11(1), (2020): 678, doi:10.1038/s41467-020-14423-9.Tropical cyclones are one of the most destructive natural hazards and much of the damage and casualties they cause are flood-related. Accurate characterization and prediction of total water levels during extreme storms is necessary to minimize coastal impacts. While meteotsunamis are known to influence water levels and to produce severe consequences, their impacts during tropical cyclones are underappreciated. This study demonstrates that meteotsunami waves commonly occur during tropical cyclones, and that they can contribute significantly to total water levels. We use an idealized coupled ocean–atmosphere–wave numerical model to analyze tropical cyclone-induced meteotsunami generation and propagation mechanisms. We show that the most extreme meteotsunami events are triggered by inherent features of the structure of tropical cyclones: inner and outer spiral rainbands. While outer distant spiral rainbands produce single-peak meteotsunami waves, inner spiral rainbands trigger longer lasting wave trains on the front side of the tropical cyclones.We thank all the developers of COAWST, ROMS, WRF, and SWAN models. D.N. was supported by NSF grant AGS-1654831. We would like to thank Dr. K. Bagamian for her editorial and writing suggestions. We would like to thank Dr. A. Aretxabaleta for the internal US Geological Survey internal revision and suggestions

The Droplet State and the Compressibility Anomaly in Dilute 2D Electron Systems

We investigate the space distribution of carrier density and the compressibility of two-dimensional (2D) electron systems by using the local density approximation. The strong correlation is simulated by the local exchange and correlation energies. A slowly varied disorder potential is applied to simulate the disorder effect. We show that the compressibility anomaly observed in 2D systems which accompanies the metal-insulator transition can be attributed to the formation of the droplet state due to disorder effect at low carrier densities.Comment: 4 pages, 3 figure

Spin Hall effects for cold atoms in a light induced gauge potential

We propose an experimental scheme to observe spin Hall effects with cold atoms in a light induced gauge potential. Under an appropriate configuration, the cold atoms moving in a spatially varying laser field experience an effective spin-dependent gauge potential. Through numerical simulation, we demonstrate that such a gauge field leads to observable spin Hall currents under realistic conditions. We also discuss the quantum spin Hall state in an optical lattice.Comment: 4 pages; The published versio

Food Safety Knowledge and Practice Among Community in Sg. Pelek, Sepang, Selangor Darul Ehsan

Food safety is a basic requirement of food quality. It is an increasingly important public health issue to prevent and control food borne illnesses. A cross-sectional study was designed to determine level of knowledge and practice on food safety, to determine the association between knowledge and practice, and also to identify the association between socio-demographic factors and practice score of the population studied. This study was conducted among adult population in Taman Bahagia, Sungai Pelek, Sepang, Selangor Darul Ehsan. Data were collected using an interviewed structured questionnaire. A stratified random sampling was performed to obtain houses, followed by simple random sampling to select sample in the house. A total of 115 data sets were analysed using Statistical Package for Social Sciences (SPSS) version 20.0. Analysis showed that 35% of respondents have poor level of knowledge on food safety, whereas 27% of the respondents have poor level of practices on food safety. Multiple linear regression revealed that there are a significant association between education level (p<0.001), Adj b=2.57 (95% CI: 1.15, 3.99) and gender (p=0.048), Adj b=1.15 (95% CI: 0.01, 2.29) with practice score on food safety. Therefore, health promotion and education on the importance of practicing food safety at home should be focused to prevent further unwanted health effects