Perturbative and non-perturbative QCD corrections to wide-angle Compton scattering

We investigate corrections to the handbag approach for wide-angle Compton scattering off protons at moderately large momentum transfer: the photon-parton subprocess is calculated to next-to-leading order QCD and contributions from the generalized parton distribution E} are taken into account. Photon and proton helicity flip amplitudes are non-zero due to these corrections which leads to a wealth of polarization phenomena in Compton scattering. Thus, for instance, the incoming photon asymmetry or the transverse polarization of the proton are non-zero although small.Comment: 19 pages, 9 figures (using LATEX with epsfig

Hardware simulation of shuttle Ku-band antenna acquisition, volume 5

For abstract, see N78-17252

Fatigue failure of materials under broad band random vibrations

The fatigue life of material under multifactor influence of broad band random excitations has been investigated. Parameters which affect the fatigue life are postulated to be peak stress, variance of stress and the natural frequency of the system. Experimental data were processed by the hybrid computer. Based on the experimental results and regression analysis a best predicting model has been found. All values of the experimental fatigue lives are within the 95% confidence intervals of the predicting equation

Negative refraction and plano-concave lens focusing in one-dimensional photonic crystals

Negative refraction is demonstrated in one-dimensional (1D) dielectric photonic crystals (PCs) at microwave frequencies. Focusing by plano-concave lens made of 1D PC due to negative refraction is also demonstrated. The frequency-dependent negative refractive indices, calculated from the experimental data matches very well with those determined from band structure calculations. The easy fabrication of one-dimensional photonic crystals may open the door for new applications.Comment: 3 pages and 5 figure

Alternative approach to all-angle negative refraction in two-dimensional photonic crystals

We show that with an appropriate surface modification, a slab of photonic crystal can be made to allow wave transmission within the band gap. Furthermore, negative refraction and all-angle-negative-refraction (AANR) can be achieved by this surface modification in frequency windows that were not realized before in two-dimensional photonic crystals [C. Luo et al, Phys. Rev. B 65, 201104 (2002)]. This approach to AANR leads to new applications in flat lens imaging. Previous flat lens using photonic crystals requires object-image distance u+v less than or equal to the lens thickness d, u+v d. Our approach can be used to design flat lens with u+v=sd with s>>1, thus being able to image large and/or far away objects. Our results are confirmed by FDTD simulations.Comment: 5 pages, 9 eps figs in RevTex forma