Bottomonium Spectrum with Screened Potential

As a sister work of Ref.[1], we incorporate the color-screening effect due to light quark pair creation into the heavy quark-antiquark potential, and investigate the effects of screened potential on the spectrum of bottomonium. We calculate the masses, electromagnetic decays, and E1 transitions of bottomonium states. We find that the fine splittings between $\chi_{bJ}$ (J=0,1,2) states are in good agreement with experimental data, and the E1 transition rates of $\Upsilon(2S)\to\gamma\chi_{bJ}(1P)$ and $\Upsilon(3S)\to\gamma\chi_{bJ}(2P)$ (J=0,1,2) all agree with data within experimental errors. In particular, the mass of $\Upsilon(6S)$ is lowered down to match that of the $\Upsilon(11020)$, which is smaller than the predictions of the linear potential models by more than 100 MeV. Comparison between charmonium and bottomonium in some related problems is also discussed.Comment: 9 pages, Commun. Theor. Phys. (in press

A Monte-Carlo simulation of the equilibrium beam polarization in ultra-high energy electron (positron) storage rings

With the recently emerging global interest in building a next generation of circular electron-positron colliders to study the properties of the Higgs boson, and other important topics in particle physics at ultra-high beam energies, it is also important to pursue the possibility of implementing polarized beams at this energy scale. It is therefore necessary to set up simulation tools to evaluate the beam polarization at these ultra-high beam energies. In this paper, a Monte-Carlo simulation of the equilibrium beam polarization based on the Polymorphic Tracking Code(PTC) (Schmidt et al., 2002 [1]) is described. The simulations are for a model storage ring with parameters similar to those of proposed circular colliders in this energy range, and they are compared with the suggestion (Derbenev et al., 1978 [2]) that there are different regimes for the spin dynamics underlying the polarization of a beam in the presence of synchrotron radiation at ultra-high beam energies. In particular, it has been suggested that the so-called "correlated" crossing of spin resonances during synchrotron oscillations at current energies, evolves into "uncorrelated" crossing of spin resonances at ultra-high energies.Comment: submitted to and accepted by Nucl. Instrum. Meth.

Architecture Layer Based Grid Computing Security Study

With increasing grid computing application in more and more industries and sectors, grid security has grown into the most critical as well as important aspect in overall application architecture. This article, from architecture layer security dimension, studies security issue in grid computing environments, indicating architecture layer based security solutions in current grid computing and proposing grid security recommendations as well, which will contribute to further defining and analyzing security strategy in grid computing and function as a guideline to the development of grid computing technology. Keywords: grid security infrastructure; security strategy; grid computin

PKI and Its Applications in E-Commerce in China

PKI system supports user authentication, message transmission, data integrity, message storage confidentiality, and the non-repudiation of operation. PKI can completely address e-commerce security requirements and PKI technology has been applied successfully in e-commerce as well. This article studies the system compositions of e-commerce, briefly analyzes e-commerce’s applications in various countries, and highlights PKI and its applications in e-commerce in China. Keywords: Public Key Infrastructure; E-commerce; applicatio