Spectral Asymmetry of Near-Concentric Traveling Ionospheric Disturbances Due to Doppler-Shifted Atmospheric Gravity Waves

Atmospheric Gravity Waves (AGWs) excited by meteorological sources are one of the prominent sources of variability in the ionosphere. Partially-concentric Traveling Ionospheric Disturbances (TIDs) associated with AGWs launched by convective storms have been reported in Total Electron Content (TEC) data from distributed networks of Global Navigation Satellite System (GNSS) receivers. In this paper, TEC data from GNSS receivers in the COntiguous United States (CONUS) are presented to examine AGWs in the ionosphere generated by a convective thunderstorm on April 28, 2014 over Mississippi (MS) and Tennessee (TN). Our analysis of the TID perturbations in the TEC data shows zonal asymmetry of the wave frequencies. This spectral asymmetry is examined to determine the effects of the background neutral wind on the intrinsic periods of the underlying AGWs. This work shows that if the relative motion of the TID wavefronts and the background neutral wind is in the opposite direction, the intrinsic periods will decrease and if they both travel in the same direction, the intrinsic periods will increase. Furthermore, our results show that the characteristics of the TIDs observed on April 28, 2014 in the TEC over CONUS are consistent with those of underlying AGWs being excited by a point source, such as a deep convection system.

Transition to strong coupling regime in hybrid plasmonic systems: exciton-induced transparency and Fano interference

We present a microscopic model describing the transition to a strong coupling regime for an emitter resonantly coupled to a surface plasmon in a metal–dielectric structure. We demonstrate that the shape of scattering spectra is determined by an interplay of two distinct mechanisms. First is the near-field coupling between the emitter and the plasmon mode which underpins energy exchange between the system components and gives rise to exciton-induced transparency minimum in scattering spectra prior to the transition to a strong coupling regime. The second mechanism is the Fano interference between the plasmon dipole and the plasmon-induced emitter’s dipole as the system interacts with the radiation field. We show that the Fano interference can strongly affect the overall shape of scattering spectra, leading to the inversion of spectral asymmetry that was recently reported in the experiment.

Chiral separation effect for spin 3/2 fermions

Chiral Separation Effect (CSE) for systems that feature spin 3/2 fermions was considered. For the self-consistent Adler’s model with relativistic massless Rarita-Schwinger fermions (RSA model), we found that the CSE conductivity is five times larger than for massless Dirac fermions. For a model of four-fold band crossing in Rarita-Schwinger-Weyl semimetals, in which massless fermions with quasispin 3/2 exist, we calculated that the CSE conductivity is four times larger than for Weyl fermions. We show that CSE conductivity for any multi-degenerate Fermi point in topological semimetals is proportional to its Chern number and is topologically protected. Along the calculations, we proved an index theorem that relates Chern number of a Fermi-point and spectral asymmetry of the corresponding Landau band structure. The assumption that CSE for any system of chiral fermions is dictated by the corresponding Chern number is found to be correct for RSA model (and for the Dirac fermions).

Complex Sachdev-Ye-Kitaev model in the double scaling limit

We solve for the exact energy spectrum, 2-point and 4-point functions of the complex SYK model, in the double scaling limit at all energy scales. This model has a U(1) global symmetry. The analysis shows how to incorporate a chemical potential in the chord diagram picture, and we present results for the various observables also at a given fixed charge sector. In addition to matching to the spectral asymmetry, we consider an analogous asymmetry measure of the 2-point function obeying a non-trivial dependence on the operator’s dimension. We also provide the chord diagram structure for an SYK-like model that has a U(M) global symmetry at any disorder realization. We then show how to exactly compute the effect of inserting very heavy operators, with formally infinite conformal dimension. The latter separate the gravitational spacetime into several parts connected by an interface, whose properties are exactly computable at all scales. In particular, light enough states can still go between the spaces. This behavior has a simple description in the chord diagram picture.

H i deficiencies and asymmetries in HIPASS galaxies

ABSTRACT We present an analysis of the sky distribution of neutral hydrogen (H i) deficiency and spectral asymmetry for galaxies detected by the H i Parkes All-Sky Survey (HIPASS) as a function of projected environment density. Previous studies of galaxy H i deficiency using HIPASS were sensitive to galaxies that are extremely H i rich or poor. We use an updated binning statistic for measuring the global sky distribution of H i deficiency that is sensitive to the average deficiencies. Our analysis confirms the result from previous studies that galaxies residing in denser environments, such as Virgo, are on average more H i deficient than galaxies at lower densities. However, many other individual groups and clusters are not found to be on average significantly H i poor, in contradiction to previous work. In terms of H i spectral asymmetries, we do not recover any significant trend of increasing asymmetry with environment density as found for other galaxy samples. We also investigate the correlation between H i asymmetry and deficiency, but find no variation in the mean asymmetry of galaxies that are H i rich, normal, or poor. This indicates that there is either no dependence of asymmetry on H i deficiency, or a galaxy’s H i deficiency only has a small influence on the measured H i asymmetry that we are unable to observe using only integrated spectra.

Transport Properties in Dense QCD Matter

Transport properties of dense QCD matter are discussed. Using the Kubo formula for conductivity, we discuss some topological aspects of quark matter during the chiral transition. The close relation to Weyl semimetal is pointed out and anomalous Hall effect is demonstrated to be possible. In particular, it is shown that the spectral asymmetry of the quasi-particles plays an important role for the Hall conductivity in the magnetic field.