Hadronic Decays Involving Heavy Pentaquarks

Recently several experiments have reported evidences for pentaquark $\Theta^+$. H1 experiment at HERA-B has also reported evidence for $\Theta_c$. $\Theta^+$ is interpreted as a bound state of an $\bar s$ with other four light quarks $udud$ which is a member of the anti-decuplet under flavor $SU(3)_f$. While $\Theta_c$ is a state by replacing the $\bar s$ in $\Theta^+$ by a $\bar c$. One can also form $\Theta_b$ by replacing the $\bar s$ by a $\bar b$. The charmed and bottomed heavy pentaquarks form triplets and anti-sixtets under $SU(3)_f$. We study decay processes involving at least one heavy pentaquark using $SU(3)_f$ and estimate the decay widths for some decay modes. We find several relations for heavy pentaquarks decay into another heavy pentaquark and a $B (B^*)$ or a $D(D^*)$ which can be tested in the future. $B$ can decay through weak interaction to charmed heavy pentaquarks. We also study some $B$ decay modes with a heavy pebtaquark in the final states. Experiments at the current $B$ factories can provide important information about the heavy pentaquark properties.Comment: RevTex 20 pages. Revised version. Discussions on the recent H1 data and new references adde

Public sector unions and government financing

Unions play a significant role in the U.S. public sector. Most studies focus on unions in the private sector, but their role in the public sector is much more significant. According to the latest Current Population Survey (CPS) by the U.S. Census Bureau, more than one-third of public sector employees are union members, whereas private sector union membership is around 6%. In this paper, we examine the impact of public sector unions on the financing costs of government because the cost of financing is one of the major concerns of governments. We employ an exogenous shock induced by the Supreme Court\u27s Janus ruling to investigate how public sector unions affect government financing costs. The Janus ruling diminished the power of public sector unions by restricting compulsory union membership or payment of union fees in the public sector. Through a series of validity tests, we find that these restrictions decrease the public sector unionization rate, public sector employment, and government expenditures, supporting our identification strategy. To proxy for changes in government debt financing costs, we use secondary municipal bond yields to measure government financing costs, as these trading activities immediately reflect changes in municipal bond yields. We first conduct an event study to compute the cumulative abnormal bond returns and split the sample by unionization rate. We find that the group with high unionization rates achieve higher cumulative abnormal returns and lower yields after the Janus ruling compared to the group with low unionization rates. We then conduct our baseline regression using a difference-in-differences design and find that the decrease in public sector union power following the Janus ruling reduces the cost of government financing, as indicated by lower municipal bond yields. The effect is more pronounced in states with high unionization rates or high heavy pension liabilities, suggesting that stronger unions are more likely to increase government\u27s credit risk. We confirm the robustness of our result using a matching-based design and a staggered law initiation. We also confirm the robustness of our research design by using a placebo test in the corporate sector, as the Janus ruling exclusively affects public sector unions

Influence of peripheral refraction on myopia

The refractive status of peripheral retina, also called peripheral refraction, is the abnormal refraction in the peripheral visual field which has a certain off-axis and off-fixation angle over 30°. Animal experiments and human studies suggest that the refractive status of peripheral retina has a close relationship with myopia. Peripheral relatively hyperopia diopter can influence the myopic degree. People in different ages with the refractive status of relatively hyperopic are risk factors for myopia onset, and may be one of risk factors for myopia progression. Peripheral myopic defocus might prevent axial elongation, so as to control the myopia progression, and promote the visual acuity. This article aims to summarize the recent findings about the influence of peripheral refraction on the onset, progression and control of myopia and its relationship with eye shape, accommodation, and heritability

FDI, Market Structure and R&D Investments in China

FDI can be an important channel for developing countries’ ability to get access to new technology. The impact of FDI on domestically-owned firms’ technology development is less examined but it is frequently argued that technology externalities or demonstration effects could have a positive impact. Another and so far little examined effect of FDI on technology development in domestically-owned firms is through the impact on competition. We examine the effect of FDI on competition in the Chinese manufacturing sector and the effect of competition on firms’ R&D. Our analysis is conducted on a large dataset including all Chinese large and medium sized firms over the period 1998-2004. Our results show that FDI increases competition but there are no strong indications of competition affecting investments in R&D.China; FDI; Competition; R&D