Results 1 - 10 of 3235
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[en] The Sturmian expansions of the multiphoton transition matrix elements diverge in the case of above-threshold ionization (ATI). To get convergent expressions one must use the analytical continuation methods. The method proposed in this paper is based on the analytical continuation of the radial transition matrix elements developed earlier for the two-photon ATI and is proved to be valid for the number of photons up to nine with one additional photon involved. Transition rates for ATI of atomic hydrogen in the ground state with one extra photon by linearly polarized light are calculated. A good agreement with experiments is obtained. 19 refs.; 8 figs.; 1 table
[en] One-dimensional quantum scattering from a local potential barrier is considered. Analytical properties of the scattering amplitudes have been investigated by means of the integral equations equivalent to the Schroedinger equations. The transition and reflection amplitudes are expressed in terms of two complex functions of the incident energy, which are similar to the Jost function in partial-wave scattering. These functions are entire for finite-range potentials and meromorphic for exponentially decreasing potentials. The analytical properties result from the locality of the potential in the wave equation and represent the effect of causality in the time dependence of the scattering process. (author)
[en] This paper discusses whether it is advisable to use exchange and overlap corrections in calculations of the relation between the relative changes in the electron-capture probabilities Δλ/λ and in the electron density at the nucleus Δρ/ρ. It is clearly shown that such corrections are not needed for Δλ/λ measurements obtained from total electron capture decay rates. (orig.)
[en] In this paper, we tried to reduce the velocity-changing-collision (VCC) effects in an La hollow cathode discharge lamp by a polarization intermodulated excitation(POLINEX) method. For an atomic excitation laser, we used a single-mode tunable diode laser with an external cavity. The power of the diode laser was amplified to more than 500 mW by using a master-oscillator power-amplifier (MOPA) configuration. As a result, when a POLINEX method is adopted, we can observe a decrease of VCC effects in 675.304 transition lines of La, compared with the case of saturation absorption spectroscopy
[en] We work with gauge systems and using gauge invariant functions we study its quantum counterpart and we find if all these operators are self adjoint or not. Our study is divided in two cases, when we choose clock or clocks that its Poisson brackets with the set of constraints is one or it is different to one. We show some transition amplitudes.
[en] Tree-level two-point jf → j′f′ transitions amplitudes in a constant uniform magnetic field of an arbitrary strength and in charged fermion plasma, for different combinations of scalar, pseudoscalar, vector, and axial-vector vertices are calculated. The obtained results are applied to analysis of the neutrino photoproduction process, γe → , taking account of a possible resonance on the virtual electron in the conditions of dense strongly magentized plasma.