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Full-Text Articles in Physical Sciences and Mathematics
Evaluation Of Laser-Assisted Bremsstrahlung With Dirac-Volkov Propagators, Erik Lotstedt, Ulrich D. Jentschura, Christoph H. Keitel
Evaluation Of Laser-Assisted Bremsstrahlung With Dirac-Volkov Propagators, Erik Lotstedt, Ulrich D. Jentschura, Christoph H. Keitel
Physics Faculty Research & Creative Works
We study spontaneous bremsstrahlung emission in a highly intense laser field. In this regime the interaction with the laser field has to be treated nonperturbatively by using the relativistic formalism including Dirac-Volkov propagators, while the interaction with the Coulomb field and the bremsstrahlung radiation can be treated in first-order perturbation theory. For the intermediate electron state a fully laser-dressed propagator is used, including radiative corrections to avoid singularities on the mass shell. We find that the use of the Dirac-Volkov propagator is crucial to obtain correct numerical results. The cross section of the process is evaluated for laser intensities of …
Theoretical Treatment Of Electron-Impact Ionization Of Molecules, Junfang Gao, Jerry Peacher, Don H. Madison
Theoretical Treatment Of Electron-Impact Ionization Of Molecules, Junfang Gao, Jerry Peacher, Don H. Madison
Physics Faculty Research & Creative Works
There is currently no reliable theory for calculating the fully differential cross section (FDCS) for low energy electron-impact ionization of molecules. All of the existing experimental FDCS data represent averages over all molecular orientations and this can be an important theoretical complication for calculations that are computer intensive. We have found that using an averaged molecular orbital is an accurate approximation for ionization of ground states. In this paper, we will describe the approximation, discuss its expected range of validity and show some FDCS results using the approximation for ionization of H2 and N2
Effect Of Amplification On Conductance Distribution Of A Disordered Waveguide, Alexey Yamilov, Hui Cao
Effect Of Amplification On Conductance Distribution Of A Disordered Waveguide, Alexey Yamilov, Hui Cao
Physics Faculty Research & Creative Works
Introduction of optical gain in a disordered system results in enhanced fluctuations [F(2)=var(g-tilde)/2] of the dimensionless conductance g-tilde, similar to the effect of Anderson localization in a passive medium. Using numerical simulations we demonstrate that, despite such qualitative similarity, the whole distribution of the conductance of amplifying random media is drastically different from that of a passive system with the same value of F(2).
Calculation Of Hydrogenic Bethe Logarithms For Rydberg States, Ulrich D. Jentschura, Peter J. Mohr
Calculation Of Hydrogenic Bethe Logarithms For Rydberg States, Ulrich D. Jentschura, Peter J. Mohr
Physics Faculty Research & Creative Works
We describe the calculation of hydrogenic (one-loop) Bethe logarithms for all states with principal quantum numbers 200. While, in principle, the calculation of the Bethe logarithm is a rather easy computational problem involving only the nonrelativistic (Schrdinger) theory of the hydrogen atom, certain calculational difficulties affect highly excited states, and in particular states for which the principal quantum number is much larger than the orbital angular momentum quantum number. Two evaluation methods are contrasted. One of these is based on the calculation of the principal value of a specific integral over a virtual photon energy. The other method relies directly …
Self-Energy Values For P States In Hydrogen And Low-Z Hydrogenlike Ions, Ulrich D. Jentschura, Peter J. Mohr
Self-Energy Values For P States In Hydrogen And Low-Z Hydrogenlike Ions, Ulrich D. Jentschura, Peter J. Mohr
Physics Faculty Research & Creative Works
We describe a nonperturbative (in Z α ) numerical evaluation of the one-photon electron self-energy for 3P1/2 , 3P3/2 , 4P1/2, and 4P3/2 states in hydrogenlike atomic systems with charge numbers Z = 1 to 5. The numerical results are found to be in agreement with known terms in the expansion of the self-energy in powers of Z α and lead to improved theoretical predictions for the self-energy shift of these states.
Static Pairwise Annihilation In Complex Networks, M. F. Laguna, M. Aldana, H. Larralde, V. M. Kenkre, Paul Ernest Parris
Static Pairwise Annihilation In Complex Networks, M. F. Laguna, M. Aldana, H. Larralde, V. M. Kenkre, Paul Ernest Parris
Physics Faculty Research & Creative Works
We study static annihilation on complex networks, in which pairs of connected particles annihilate at a constant rate during time. Through a mean-field formalism, we compute the temporal evolution of the distribution of surviving sites with an arbitrary number of connections. This general formalism, which is exact for disordered networks, is applied to Kronecker, Erdös-Rényi (i.e., Poisson), and scale-free networks. We compare our theoretical results with extensive numerical simulations obtaining excellent agreement. Although the mean-field approach applies in an exact way neither to ordered lattices nor to small-world networks, it qualitatively describes the annihilation dynamics in such structures. Our results …
Self-Energy Correction To The Two-Photon Decay Width In Hydrogenlike Atoms, Ulrich D. Jentschura
Self-Energy Correction To The Two-Photon Decay Width In Hydrogenlike Atoms, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
We investigate the guage invariance of the leading logarithmic radiative correction to the two-photon decay width in hydrogenlike atoms, was investigated. The effective treatment of the correction using a Lamb-shift led to the equivalent results in both the length and velocity gages. The relevant radiative corrections were found to be related to the energies that entered into the propagator denominators, to the Hamiltonian, to the wave functions, and to the energy conservation condition, that holds between two photons. The results show that the dominant radiative correction to the 2S two-photon decay width is about -2.020 536(α/π)(Zα)2 1n[(Zα)-2] …
Charge Transfer In Slow Collisions Of C⁴⁺ With H Below 1 Kev/Amu, Chen-Nan Liu, Anh-Thu Le, C. D. Lin
Charge Transfer In Slow Collisions Of C⁴⁺ With H Below 1 Kev/Amu, Chen-Nan Liu, Anh-Thu Le, C. D. Lin
Physics Faculty Research & Creative Works
We reexamined charge-transfer cross sections for C⁴⁺ + H collisions for energies from 1 meV/amu to 1 keV/amu using the recently developed hyperspherical close-coupling method. Our results agree with several previous theoretical calculations using molecular-orbital expansion. However, these converged theoretical predictions do not agree with total cross sections from the merged-beam experiments.
Asymptotic Properties Of Self-Energy Coefficients, Ulrich D. Jentschura, Eric Olivier Le Bigot, Peter J. Mohr, Paul Indelicato, Gerhard Soff
Asymptotic Properties Of Self-Energy Coefficients, Ulrich D. Jentschura, Eric Olivier Le Bigot, Peter J. Mohr, Paul Indelicato, Gerhard Soff
Physics Faculty Research & Creative Works
We investigate the asymptotic properties of higher-order binding corrections to the one-loop self-energy of excited states in atomic hydrogen. We evaluate the historically problematic A60 coefficient for all P states with principal quantum numbers n ≤ 7 and D states with n ≤ 8 and find that a satisfactory representation of the n dependence of the coefficients requires a three-parameter fit. For the high-energy contribution to A60, we find exact formulas. The results obtained are relevant for the interpretation of high-precision laser spectroscopic measurements.
Resummation Of The Divergent Perturbation Series For A Hydrogen Atom In An Electric Field, Ulrich D. Jentschura
Resummation Of The Divergent Perturbation Series For A Hydrogen Atom In An Electric Field, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
We consider the resummation of the perturbation series describing the energy displacement of a hydrogenic bound state in an electric field (known as the Stark effect or the LoSurdo-Stark effect), which constitutes a divergent formal power series in the electric-field strength. The perturbation series exhibits a rich singularity structure in the Borel plane. Resummation methods are presented that appear to lead to consistent results even in problematic cases where isolated singularities or branch cuts are present on the positive and negative real axis in the Borel plane. Two resummation prescriptions are compared: (i) a variant of the Borel-Pad'e resummation method, …