Positron scattering and annihilation on noble-gas atoms is studied ab initio using many-
body theory methods for positron energies below the positronium formation threshold. We …

A many-body theory approach is developed for the problem of positron-atom scattering and
annihilation. Strong electron-positron correlations are included nonperturbatively through …

The parameters that determine the nondipole (E 1− E 2) corrections to the photoelectron
angular distribution have been investigated for the s− and p-subshells of the noble-gas …

A many-body-theory approach has been developed to study positronium-atom interactions.
As first applications, we calculate the elastic scattering and momentum-transfer cross …

The parameter that determines the nondipole correction to the angular distribution is
calculated for Ar 1 s and 3 s subshells in the Hartree-Fock (HF) approximation and taking …

Although breakdowns in the dipole approximation in the soft-X-ray photon-energy range
(hν≤ 5 keV) were first observed 30 years ago and have been studied theoretically for many …

It is found that electric-dipole–electric-quadrupole E 1-E 2 interference effects at low photon
energies, of the order of tens of eV, in photoelectron angular distributions can be significant …

The random-phase approximation (RPA) is applied to study nondipole corrections to the
angular distribution of photoelectrons from the n= 2 shell of Ne. Calculations of the …

The contribution of electric-dipole-electric-quadrupole interference terms (the lowest-order
non-dipole corrections) to the spin polarization of photoelectrons ejected from atomic np …

We review here the current status of atomic and molecular HAXPES, both experimentally
and theoretically. After the era of the ESCA technique, atomic and molecular HAXPES …