Intensities of the line and photoionization spectra of shallow nonhydrogenlike impurities in semiconductors

Numerical nonvariational methods are proposed for the calculation of energies and wave functions of bound states, ground state wave functions with the account of central cell corrections, and the orthonormalized wave functions of the continuous spectrum of nonhydrogenlike shallow impurities in semiconductors. A number of different spectral characteristics is calculated for donor impurities in Ge and Si and for acceptor impurities in Ge and GaAs. The theory of photofield ionization i.e. tunnel ionization of an optically excited impurity atom is presented for shallow donors with the account of the effective mass anisotropy. The possibility of the observation of the line spectrum (due to transitions to shallow Coulomb excited levels) of a deep impurity in the presence of a high magnetic field is shown.     

Calculation of electromagnetic ρπ formfactor from QCD sum rules

Electromagnetic ρπ formfactor at intermediate momentum transfer, 0.7 GeV²≦Q ²≦3 GeV², is calculated using QCD sum rules for the vertex function of two vector and one axial vector currents. In this region the results obtained are consistent within 25% accuracy with the vector meson dominance model predictions and can be regarded as its theoretical justification.