Nonleptonic Weak Decays of Bottom Baryons

Cabibbo-allowed two-body hadronic weak decays of bottom baryons are analyzed. Contrary to the charmed baryon sector, many channels of bottom baryon decays proceed only through the external or internal W-emission diagrams. Moreover, W-exchange is likely to be suppressed in the bottom baryon sector. Consequently, the factorization approach suffices to describe most of the Cabibbo-allowed bottom baryon decays. We use the nonrelativistic quark model to evaluate heavy-to-heavy and heavy-to-light baryon form factors at zero recoil. When applied to the heavy quark limit, the quark model results do satisfy all the constraints imposed by heavy quark symmetry. The decay rates and up-down asymmetries for bottom baryons decaying into $(1/2)^++P(V)$ and $(3/2)^++P(V)$ are calculated. It is found that the up-down asymmetry is negative except for $\Omega_b \to (1/2)^++P(V)$ decay and for decay modes with $\psi'$ in the final state. The prediction $B(\Lambda_b \to J/\psi\Lambda)=1.6 \times 10^{-4}$ for $|V_{cb}|=0.038$ is consistent with the recent CDF measurement. We also present estimates for $\Omega_c \to (3/2)^++P(V)$ decays and compare with various model calculations.Comment: 24 pages, to appear in Phys. Rev. Uncertainties with form factor q^2 dependence are discusse

Evaluation on the Effects of Deicing Chemicals on Soil and Water Environment

AbstractDeicing chemicals are widely used to clear the pavement snow in the cold areas of China and many other countries in winter, because of their simple operation and excellent snow-melting effect, which leads to more convenience for traffic and low probability of traffic accident in the city, especially in metropolis. However, with the ever-growing application of deicing chemicals, their negative effects on environment such as soil and water system increased dramatically. Based on the related researches in China and abroad, this paper summarized the two categories of deicing chemicals and their working principles, and then provided the unique characteristics of deicing chemicals’ effects on soil and water environment in large cities, which may need considerable quantity of the chemicals to relieve traffic congestion. What's more, main aspects of impacts by deicing chemicals on regional soil and water environment and the fundamental factors related to the aspects above respectively were generalized, in order to propose a conceptual model to evaluate the harmful effects. Moreover, this paper put forward some suggestions for the further research in this field to fulfill the model, and provided a scientific basis for the pollution prevention of deicing chemicals on urban environment

Charmless Exclusive Baryonic B Decays

We present a systematical study of two-body and three-body charmless baryonic B decays. Branching ratios for two-body modes are in general very small, typically less than $10^{-6}$, except that \B(B^-\to p \bar\Delta^{--})\sim 1\times 10^{-6}. In general, $\bar B\to N\bar\Delta>\bar B\to N\bar N$ due to the large coupling constant for $\Sigma_b\to B\Delta$. For three-body modes we focus on octet baryon final states. The leading three-dominated modes are $\bar B^0\to p\bar n\pi^-(\rho^-), n\bar p\pi^+(\rho^+)$ with a branching ratio of order $3\times 10^{-6}$ for $\bar B^0\to p\bar n\pi^-$ and $8\times 10^{-6}$ for $\bar B^0\to p\bar n\rho^-$. The penguin-dominated decays with strangeness in the meson, e.g., $B^-\to p\bar p K^{-(*)}$ and $\bar B^0\to p\bar n K^{-(*)}, n\bar n \bar K^{0(*)}$, have appreciable rates and the $N\bar N$ mass spectrum peaks at low mass. The penguin-dominated modes containing a strange baryon, e.g., $\bar B^0\to \Sigma^0\bar p\pi^+, \Sigma^-\bar n\pi^+$, have branching ratios of order $(1\sim 4)\times 10^{-6}$. In contrast, the decay rate of $\bar B^0\to\Lambda\bar p\pi^+$ is smaller. We explain why some of charmless three-body final states in which baryon-antibaryon pair production is accompanied by a meson have a larger rate than their two-body counterparts: either the pole diagrams for the former have an anti-triplet bottom baryon intermediate state, which has a large coupling to the $B$ meson and the nucleon, or they are dominated by the factorizable external $W$-emission process.Comment: 46 pages and 3 figures, to appear in Phys. Rev. D. Major changes are: (i) Calculations of two-body baryonic B decays involving a Delta resonance are modified, and (ii) Penguin-dominated modes B-> Sigma+N(bar)+p are discusse

Study on vibration and stability of functionally graded cylindrical shells subjected to hydrostatic pressure

Based on the Flügge’s shell theory, the vibration characteristics and stability of submerged functionally graded (FG) cylindrical shell under hydrostatic pressure is examined. By means of conversion switch on axial wave number, the coupled frequency of submerged FG cylindrical shell with various boundary conditions is obtained, using wave propagation method and Newton method. Then the critical pressure of FG cylindrical shells is given by applying linear fitting method. Results are compared to known solutions, where these solutions exist. The natural frequency and critical pressure of FG cylindrical shell are illustrated. The effects of constituent materials, volume fraction, boundary condition and dimensions on the natural frequencies and critical pressures of submerged FG cylindrical shell are illustrated by examples

Stomach One-Point Cancer: One Case Report and Literature Review

Gastric cancer is one of the most common cancers and one of themost frequent causes of cancer deaths worldwide. Early detection andaccurate preoperative staging of gastric cancer is essential for planning optimal therapy such as endoscopic mucosal resection or gastric resection and offers the best prognosis. With advanced technology in diagnostic instruments and the mass screening, early gastric cancer has been detected easier. One-point cancer of gastric is a special type of early gastric cancer[1]. Diagnosis of one-point cancer of gastric is important for both the immediate treatment and the prognosis. There is still no consensus on the operation extent and postoperative treatment for patients with one-point cancer of gastric. Learned from previous reports[2-5], we know that existed in the superfi cial layer of the gastric mucosa and the superfi cial ulcer is one of the important characteristics of one point cancer of gastric. Herein, we report a case of one point cancer of gastric with the appearance of a deep infi ltrating ulcer. To the best of our knowledge, no such type of one point cancer of gastric has been reported

Study on vibration and stability of functionally graded cylindrical shells subjected to hydrostatic pressure

Based on the Flügge’s shell theory, the vibration characteristics and stability of submergedfunctionally graded (FG) cylindrical shell under hydrostatic pressure is examined. By means of conversionswitch on axial wave number, the coupled frequency of submerged FG cylindrical shell with variousboundary conditions is obtained, using wave propagation method and Newton method. Then the criticalpressure of FG cylindrical shells is given by applying linear fitting method. Results are compared to knownsolutions, where these solutions exist. The natural frequency and critical pressure of FG cylindrical shell are illustrated. The effects of constituent materials, volume fraction, boundary condition and dimensions on the natural frequencies and critical pressures of submerged FG cylindrical shell are illustrated by examples.2nd International Symposium on Engineering Mechanics and its Applications, Kitakyushu, Japan, 30 – 31 August 201

Analysis of Two-Body Decays of Charmed Baryons Using the Quark-Diagram Scheme

We give a general formulation of the quark-diagram scheme for the nonleptonic weak decays of baryons. We apply it to all the decays of the antitriplet and sextet charmed baryons and express their decay amplitudes in terms of the quark-diagram amplitudes. We have also given parametrizations for the effects of final-state interactions. For SU(3) violation effects, we only parametrize those in the horizontal $W$-loop quark diagrams whose contributions are solely due to SU(3)-violation effects. In the absence of all these effects, there are many relations among various decay modes. Some of the relations are valid even in the presence of final-state interactions when each decay amplitude in the relation contains only a single phase shift. All these relations provide useful frameworks to compare with future experiments and to find out the effects of final-state interactions and SU(3) symmetry violations.Comment: 28 pages, 20 Tables in landscape form, 4 figures. Main changes are: (i) some errors in the Tables and in the relations between the quark-diagram amplitudes of this paper and those of Ref.[10] are corrected, (ii) improvements are made in the presentation so that comparisons with previous works and what have been done to include SU(3) breaking and final-state interactions are more clearly stated; to appear in the Physical Review

Meta-stable SUSY Breaking Model in Supergravity

We analyze a supersymmetry (SUSY) breaking model proposed by Intriligator, Seiberg and Shih in a supergravity (SUGRA) framework. This is a simple and natural setup which demands neither extra superpotential interactions nor an additional gauge symmetry. In the SUGRA setup, the U(1)R symmetry is explicitly broken by the constant term in the superpotential, and pseudo-moduli field naturally takes non-zero vacuum expectation value through a vanishing cosmological constant condition. Sfermions tend to be heavier than gauginos, and the strong-coupling scale is determined once a ratio of sfermion to gaugino masses is fixed.Comment: 13 page

Studies of the electric dipole transitions of deformed rare-earth nuclei

Spectrum and electric dipole transition rates and relative intensities in $^{152-154}$Sm, $^{156-160}$Gd, $^{160-162}$Dy are studied in the framework of the interacting boson model with s,p,d,f bosons. It is found that E1 transition data among the low-lying levels are in good agreement with the SU(3) dynamical symmetry of the spdf interacting boson model proposed by Engel and Iachello to describe collective rotation with octupole vibration. These results show that these nuclei have SU(3) dynamic symmetry to a good approximation. Also in this work many algebraic expressions for electric dipole transitions in the SU(3) limit of the spdf-IBM have been obtained. These formulae together with the formulae given previously exhaust nearly all the E1 transitions for low-lying negative parity states. They are useful in analyzing experimental data.Comment: 26 pages, 1 figur