Relativistic Coulomb Green's function in dd-dimensions

Using the operator method, the Green's functions of the Dirac and Klein-Gordon equations in the Coulomb potential $-Z\alpha/r$ are derived for the arbitrary space dimensionality $d$. Nonrelativistic and quasiclassical asymptotics of these Green's functions are considered in detail.Comment: 9 page

DRA method: Powerful tool for the calculation of the loop integrals

We review the method of the calculation of multiloop integrals suggested in Ref.\cite{Lee2010}.Comment: 6 pages, contribution to ACAT2011 proceedings, Uxbridge, London, September 5-9, 2011, typos are correcte

Planetary companions orbiting M giants HD 208527 and HD 220074

Aims. The purpose of the present study is to research the origin of planetary companions by using a precise radial velocity (RV) survey. Methods. The high-resolution spectroscopy of the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at Bohyunsan Optical Astronomy Observatory (BOAO) is used from September 2008 to June 2012. Results. We report the detection of two exoplanets in orbit around HD 208527 and HD 220074 exhibiting periodic variations in RV of 875.5 +/- 5.8 and 672.1 +/- 3.7 days. The RV variations are not apparently related to the surface inhomogeneities and a Keplerian motion of the planetary companion is the most likely explanation. Assuming possible stellar masses of 1.6 +/- 0.4 and 1.2 +/- 0.3 M_Sun, we obtain the minimum masses for the exoplanets of 9.9 +/- 1.7 and 11.1 +/- 1.8 M_Jup around HD 208527 and HD 220074 with an orbital semi-major axis of 2.1 +/- 0.2 and 1.6 +/- 0.1 AU and an eccentricity of 0.08 and 0.14, respectively. We also find that the previously known spectral classification of HD 208527 and HD 220074 was in error: Our new estimation of stellar parameters suggest that both HD 208527 and HD 220074 are M giants. Therefore, HD 208527 and HD 220074 are so far the first candidate M giants to harbor a planetary companion.Comment: 7 pages, 9 figures, 4 tables, accepted for publisation in Astronomy & Astrophysic

Power Spectral Density of Magnetization Dynamics Driven by a Jump-Noise Process

Random magnetization dynamics driven by a jump-noise process is reduced to stochastic magnetic energy dynamics on specific graphs using an averaging technique. An approach to analyzing stochastic energy dynamics on graphs is presented and applied to the calculation of power spectral density of random magnetization dynamics. An eigenvalue technique for computing the power spectral density under specific cases is also presented and illustrated by numerical results

Investigation of empennage buffeting

Theoretical methods of predicting aircraft buffeting are reviewed. For the buffeting due to leading-edge vortex breakdown, a method is developed to convert test data of mean square values of fluctuating normal force to buffeting vortex strength through an unsteady lifting-surface theory and unsteady suction analogy. The resulting buffeting vortex from the leading-edge extension of an F-18 configuration is used to generate a fluctuating flow field which produces unsteady pressure distribution on the vertical tails. The root mean square values of root bending moment on the vertical tails are calculated for a rigid configuration. Results from a flow visualization and hot films study in a water tunnel facility using a 1/48 scale model of an F-18 are included in an appendix. The results confirm that the LEX vortex is the dominant forcing function of fin buffet at high angles of attack

GaAs-GaAIAs injection lasers on semi-insulating substrates using laterally diffused junctions

Low‐threshold GaAs‐GaAlAs lasers operating in a stable single mode have been fabricated using laterally diffused junctions. The lasers are fabricated on semi‐insulating substrates and can be integrated with other components

Embedded heterostructure epitaxy: A technique for two-dimensional thin-film definition

Selective multilayer epitaxial growth of GaAs-Ga1–xAlxAs through stripe openings in Al2O3 mask is reported. The technique results in prismatic layers of GaAs and Ga1–xAlxAs "embedded" in each other and leads to controllable uniform structures terminated by crystal faces. The crystal habit (shape) has features which are favorable for fabrication of cw injection lasers, laser arrays, and integrated optics components which require planar definition

Integration of an injection laser with a Gunn oscillator on a semi-insulating GaAs substrates

The integration of an injection semiconductor laser with an active electronic device (Gunn oscillator) in a single epitaxial crystal device is demonstrated

Low-threshold room-temperature embedded heterostructure lasers

Room-temperature embedded double-heterostructure injection lasers have been fabricated using selective liquid phase epitaxial growth. Threshold current densities as low as 1.5 kA/cm^2 have been achieved in lasers grown through stripe windows opened in epitaxial GaAlAs masks

Investigating the Physical Origin of Unconventional Low-Energy Excitations and Pseudogap Phenomena in Cuprate Superconductors

We investigate the physical origin of unconventional low-energy excitations in cuprate superconductors by considering the effect of coexisting competing orders (CO) and superconductivity (SC) and of quantum fluctuations and other bosonic modes on the low-energy charge excitation spectra. By incorporating both SC and CO in the bare Green's function and quantum phase fluctuations in the self-energy, we can consistently account for various empirical findings in both the hole- and electron-type cuprates, including the excess subgap quasiparticle density of states, ``dichotomy'' in the fluctuation-renormalized quasiparticle spectral density in momentum space, and the occurrence and magnitude of a low-energy pseudogap being dependent on the relative gap strength of CO and SC. Comparing these calculated results with experiments of ours and others, we suggest that there are two energy scales associated with the pseudogap phenomena, with the high-energy pseudogap probably of magnetic origin and the low-energy pseudogap associated with competing orders.Comment: 10 pages, 5 figures. Invited paper for the 2006 Taiwan International Conference on Superconductivity. Correspondence author: Nai-Chang Yeh (e-mail: [email protected]