Relativistic Corrections to e+e−→J/ψ+ηce^+e^- \to J/\psi + \eta_c in a Potential Model

We compute relativistic corrections to the process $e^+e^- \to J/\psi + \eta_c$ and find that they resolve the discrepancy between theory and experiment.Comment: 3 pages, talk given at Quark Confinement and the Hadron Spectrum VII, Ponta Delgada, Azores, 2--7 Sept, 200

Two Essays on Corporate Finance

Department of Management EngineeringIn the first essay entitled ???The Season of Risk: CEO Season of Birth and Corporate Risk-taking???, we provide new evidence on the relation between CEO personal risk-seeking preference and corporate risk-taking. Consistent with the theoretical prediction of behavioral consistency theory, we find evidence that winter-born CEOs, who were most likely to be in the early embryonic development stage during the period of the longest day-length, are associated with the riskiness of their firms. Winter-born CEOs carry greater firm risk, beyond the level explained by managerial incentives included by compensation structures. We attribute the potential source of the increased firm risk to financial and investment policies, including financial leverage, debt maturity, asset liquidity, and investment in intangible and tangible assets. Our findings support the notion that the inherent personality traits of CEOs have important implications for corporate risk-taking. In the second essay entitled ???Co-opted Boards and Stock Price Crash Risk???, we investigate the association between co-opted boards and the risk of a stock price crash with a large sample of U.S. firms for the period 1996???2014. Our main finding holds for various robustness tests. Further analyses show that the effect of co-option on stock price crash risk is amplified when CEOs are more concerned about their careers. Overall, our findings suggest that board co-option appears to decrease the effectiveness of board monitoring, and that the role of board monitoring is particularly important when the CEO has a stronger incentive to withhold negative information.clos

Singlet Fermionic Dark Matter with Dark ZZ

We present a fermionic dark matter model mediated by the hidden gauge boson. We assume the QED-like hidden sector which consists of a Dirac fermion and U(1)$_X$ gauge symmetry, and introduce an additional scalar electroweak doublet field with the U(1)$_X$ charge as a mediator. The hidden U(1)$_X$ symmetry is spontaneously broken by the electroweak symmetry breaking and there exists a massive extra neutral gauge boson in this model which is the mediator between the hidden and visible sectors. Due to the U(1)$_X$ charge, the additional scalar doublet does not couple to the Standard Model fermions, which leads to the Higgs sector of type I two Higgs doublet model. The new gauge boson couples to the Standard Model fermions with couplings proportional to those of the ordinary $Z$ boson but very suppressed, thus we call it the dark $Z$ boson. We study the phenomenology of the dark $Z$ boson and the Higgs sector, and show the hidden fermion can be the dark matter candidate.Comment: 10 pages, 3 figure

Scandium Doping Effect on a Layered Perovskite Cathode for Low-Temperature Solid Oxide Fuel Cells (LT-SOFCs)

Layered perovskite oxides are considered as promising cathode materials for the solid oxide fuel cell (SOFC) due to their high electronic/ionic conductivity and fast oxygen kinetics at low temperature. Many researchers have focused on further improving the electrochemical performance of the layered perovskite material by doping various metal ions into the B-site. Herein, we report that Sc3+ doping into the layered perovskite material, PrBaCo2O5+ (PBCO), shows a positive effect of increasing electrochemical performances. We confirmed that Sc3+ doping could provide a favorable crystalline structure of layered perovskite for oxygen ion transfer in the lattice with improved Gold-schmidt tolerance factor and specific free volume. Consequently, the Sc3+ doped PBCO exhibits a maximum power density of 0.73 W cm(-2) at 500 degrees C, 1.3 times higher than that of PBCO. These results indicate that Sc3+ doping could effectively improve the electrochemical properties of the layered perovskite material, PBCO

FePt nanodot arrays with perpendicular easy axis, large coercivity, and extremely high density

Ordered FePt nanodot arrays with extremely high density have been developed by physical vapor deposition using porous alumina templates as evaporation masks. Nanodot diameter of 18 nm and periodicity of 25 nm have been achieved, resulting in an areal density exceeding 1 x1012 dots/in2. Rapid thermal annealing converts the disordered fcc to L10 phase, resulting in (001)-oriented FePt nanodot arrays with perpendicular anisotropy and large coercivity, without the need of epitaxy. High anisotropy and coercivity, perpendicular easy axis orientation and extremely high density are desirable features for future magnetic data storage media applications