Accounting for correlations with core electrons by means of the generalized relativistic effective core potentials: Atoms Hg and Pb and their compounds

A way to account for correlations between the chemically active (valence) and innermore (core) electrons in the framework of the generalized relativistic effective core potential (GRECP) method is suggested. The "correlated" GRECP's (CGRECP's) are generated for the Hg and Pb atoms. Only correlations for the external twelve and four electrons of them, correspondingly, should be treated explicitly in the subsequent calculations with these CGRECP's whereas the innermore electrons are excluded from the calculations. Results of atomic calculations with the correlated and earlier GRECP versions are compared with the corresponding all-electron Dirac-Coulomb values. Calculations with the above GRECP's and CGRECP's are also carried out for the lowest-lying states of the HgH molecule and its cation and for the ground state of the PbO molecule as compared to earlier calculations and experimental data. The accuracy for the vibrational frequencies is increased up to an order of magnitude and the errors for the bond lengths (rotational constants) are decreased in about two times when the correlated GRECP's are applied instead of earlier GRECP versions employing the same innercore-outercore-valence partitioning.Comment: 12 pages, 4 tables, the text of the paper was significantly improve

In-medium modification and decay asymmetry of omega mesons in cold nuclear matter

We discuss an asymmetry of the decay $\omega->e^+e^-$ in nuclear matter with respect to the electron and positron energies. This asymmetry is sensitive to the properties of the $\omega$ meson self-energy and, in particular, it has a non-trivial dependence on the $\omega$ energy and momentum. Therefore, this asymmetry may serve as a powerful tool in studying the properties of the $\omega$ meson in the nuclear medium.Comment: 19 pages, 9 figure

Electromagnetic modulation of monochromatic neutrino beams

A possibility to produce a modulated monochromatic neutrino beam is discussed. Monochromatic neutrinos can be obtained in electron capture by nuclei of atoms or ions, in particular, by nuclei of hydrogen-like ions. It is shown that monochromatic neutrino beam from such hydrogen-like ions with nuclei of non-zero spin can be modulated because of different probabilities of electron capture from hyperfine states. Modulation arises by means of inducing of electromagnetic transitions between the hyperfine states. Requirements for the hydrogen-like ions with necessary properties are discussed. A list of the appropriate nuclei for such ions is presented.Comment: 11 pages, 1 figure, minor corrections to match the final published versio

Selected vector-meson decay-distributions in reactions of polarized photons with protons

We develop a formalism for studying vector meson ($V$) photo-production at the proton ($p$) with polarized photons, $\vec\gamma p \to V p$, through an analysis of the decay distribution in the channel $V\to\pi^0\gamma$. We show that this decay distribution differs noticeably from the distributions of purely hadronic decays, like $\phi\to K^+K^-$, $\omega\to \pi^0\pi^+\pi^-$. Formulas for the decay distributions are presented which are suitable for data analysis and interpretation.Comment: 3 pages, 2 figure

Isoscalar-Isovector Interferences in πN→Ne+e−\pi N \to N e^+ e^- Reactions as a Probe of Baryon Resonance Dynamics

The isoscalar-isovector ($\rho-\omega$) interferences in the exclusive reactions $\pi^- p \to n e^+ e^-$ and $\pi^+ n \to p e^+ e^-$ near the $\omega$ threshold leads to a distinct difference of the dielectron invariant mass distributions depending on beam energy. The strength of this effect is determined by the coupling of resonances to the nucleon vector-meson channels and other resonance properties. Therefore, a combined analysis of these reactions can be used as a tool for determining the baryon resonance dynamics

May 12 1997 Cme Event: I. a Simplified Model of the Pre-Eruptive Magnetic Structure

A simple model of the coronal magnetic field prior to the CME eruption on May 12 1997 is developed. First, the magnetic field is constructed by superimposing a large-scale background field and a localized bipolar field to model the active region (AR) in the current-free approximation. Second, this potential configuration is quasi-statically sheared by photospheric vortex motions applied to two flux concentrations of the AR. Third, the resulting force-free field is then evolved by canceling the photospheric magnetic flux with the help of an appropriate tangential electric field applied to the central part of the AR. To understand the structure of the modeled configuration, we use the field line mapping technique by generalizing it to spherical geometry. It is demonstrated that the initial potential configuration contains a hyperbolic flux tube (HFT) which is a union of two intersecting quasi-separatrix layers. This HFT provides a partition of the closed magnetic flux between the AR and the global solar magnetic field. The vortex motions applied to the AR interlock the field lines in the coronal volume to form additionally two new HFTs pinched into thin current layers. Reconnection in these current layers helps to redistribute the magnetic flux and current within the AR in the flux-cancellation phase. In this phase, a magnetic flux rope is formed together with a bald patch separatrix surface wrapping around the rope. Other important implications of the identified structural features of the modeled configuration are also discussed.Comment: 25 pages, 11 figures, to appear in ApJ 200

Metallic proximity effect in ballistic graphene with resonant scatterers

We study the effect of resonant scatterers on the local density of states in a rectangular graphene setup with metallic leads. We find that the density of states in a vicinity of the Dirac point acquires a strong position dependence due to both metallic proximity effect and impurity scattering. This effect may prevent uniform gating of weakly-doped samples. We also demonstrate that even a single-atom impurity may essentially alter electronic states at low-doping on distances of the order of the sample size from the impurity.Comment: 9 pages, 2 figure