Real photons produced from photoproduction in pppp collisions

We calculate the production of real photons originating from the photoproduction in relativistic $pp$ collisions. The Weizs$\ddot{\mathrm{a}}$cker-Williams approximation in the photoproduction is considered. Numerical results agree with the experimental data from Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC). We find that the modification of the photoproduction is more prominent in large transverse momentum region.Comment: 2 figure

Renormalization Group Study of the Electron-phonon Interaction in the High Tc Cuprates

We generalize the numerical renormalization group scheme to study the phonon-mediated retarded interactions in the high Tc cuprates. We find that three sets of phonon-mediated retarded quasiparticle scatterings grow under RG flow. These scatterings share the following common features: 1) the initial and final quasiparticle momenta are in the antinodal regions, and 2) the scattering amplitudes have a $x^2-y^2$ symmetry. All three sets of retarded interaction are driven to strong coupling by the magnetic fluctuations around $(\pi,\pi)$. After growing strong, these retarded interaction will trigger density wave orders with d-wave symmetry. However, due to the d-wave form factor they will leave the nodal quasiparticle unaffected. We conclude that the main effect of electron-phonon coupling in the cuprates is to promote these density wave orders.Comment: 4 pages, 3 figures, references added, added more details about others' previous studie

Determination of the η\eta-η′\eta^\prime mixing angle

We extract $\eta$-$\eta^\prime$ mixing angle and the ratios of decay constants of light pseudoscalar mesons $\pi^0$, $\eta$ and $\eta^\prime$ using recently available BaBar measurements on $\eta$-photon and $\eta^\prime$-photon transition form factors and more accurate experimental data for the masses and two-photon decay widths of the light pseduoscalar mesons.Comment: 5 pages, revtex, no figures, accepted for publication as a Brief Report in Physical Review

Reflection high-energy electron diffraction studies of the growth of lnAs/Ga_(1-x)In_xSb strained-layer superlattices

We have used reflection high‐energy electron diffraction to study the surface periodicity of the growth front of InAs/GaInSb strained‐layer superlattices (SLSs). We found that the apparent surface lattice spacing reproducibly changed during layers which subsequent x‐ray measurements indicated were coherently strained. Abrupt changes in the measured streak spacings were found to be correlated to changes in the growth flux. The profile of the dynamic streak spacing was found to be reproducible when comparing consecutive periods of a SLSs or different SLSs employing the same shuttering scheme at the InAs/GaInSb interface. Finally, when the interface shuttering scheme was changed, it was found that the dynamic streak separation profile also changed. Large changes in the shuttering scheme led to dramatic differences in the streak separation profile, and small changes in the shuttering scheme led to minor changes in the profile. In both cases, the differences in the surface periodicity profile occurred during the parts of the growth where the incident fluxes differed

Weyl points and line nodes in gapless gyroid photonic crystals

Weyl points and line nodes are three-dimensional linear point- and line-degeneracies between two bands. In contrast to Dirac points, which are their two-dimensional analogues, Weyl points are stable in the momentum space and the associated surface states are predicted to be topologically non-trivial. However, Weyl points are yet to be discovered in nature. Here, we report photonic crystals, based on the double-gyroid structures, exhibiting frequency-isolated Weyl points with intricate phase diagrams. The surface states associated with the non-zero Chern numbers are demonstrated. Line nodes are also found in similar geometries; the associated surface states are shown to be flat bands. Our results are readily experimentally realizable at both microwave and optical frequencies.Comment: 6 figures and 8 pages including the supplementary informatio