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Full-Text Articles in Physical Sciences and Mathematics
Two-Loop Bethe Logarithms For Higher Excited S Levels, Ulrich D. Jentschura
Two-Loop Bethe Logarithms For Higher Excited S Levels, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
Processes mediated by two virtual low-energy photons contribute quite significantly to the energy of hydrogenic S states. The corresponding level shift is of the order of ( α / π )2 ( Z α )6 mec2 and may be ascribed to a two-loop generalization of the Bethe logarithm. For 1 S and 2 S states, the correction has recently been evaluated by Pachucki and Jentschura [Phys. Rev. Lett. 91, 113005 (2003)]. Here, we generalize the approach to higher excited S states, which in contrast to the 1 S and 2 S states can decay to …
Effect Of Kerr Nonlinearity On Defect Lasing Modes In Weakly Disordered Photonic Crystals, Boyang Liu, Alexey Yamilov, Hui Cao
Effect Of Kerr Nonlinearity On Defect Lasing Modes In Weakly Disordered Photonic Crystals, Boyang Liu, Alexey Yamilov, Hui Cao
Physics Faculty Research & Creative Works
We studied the effect of Kerr nonlinearity on lasing in defect modes of weakly disordered photonic crystals. Our time-independent calculation based on self-consistent nonlinear transfer matrix method shows that Kerr nonlinearity modifies both frequencies and quality factors of defect modes. We also used a time-dependent algorithm to investigate the dynamic nonlinear effect. Under continuous pumping, the spatial sizes and intensities of defect lasing modes are changed by Kerr nonlinearity. Such changes are sensitive to the nonlinear response time.
Nature Of Charge Carriers In Disordered Molecular Solids: Are Polarons Compatible With Observations?, Paul Ernest Parris, Vasudev M. Kenkre, David H. Dunlap
Nature Of Charge Carriers In Disordered Molecular Solids: Are Polarons Compatible With Observations?, Paul Ernest Parris, Vasudev M. Kenkre, David H. Dunlap
Physics Faculty Research & Creative Works
Polaronic theories for charge transport in disordered organic solids, particularly molecularly doped polymers, have been plagued by issues of internal consistency related to the magnitude of physical parameters. We present a natural resolution of the problem by showing that, in the presence of correlated disorder, polaronic carriers with binding energies Δ ~ 50 - 500 meV and transfer integrals J ~ 1 - 20 meV are completely consistent with the magnitudes of field and temperature dependent mobilities observed.
Resummation Of Qed Perturbation Series By Sequence Transformations And The Prediction Of Perturbative Coefficients, Ulrich D. Jentschura, Jens Becher, Ernst Joachim Weniger, Gerhard Soff
Resummation Of Qed Perturbation Series By Sequence Transformations And The Prediction Of Perturbative Coefficients, Ulrich D. Jentschura, Jens Becher, Ernst Joachim Weniger, Gerhard Soff
Physics Faculty Research & Creative Works
We propose a method for the resummation of divergent perturbative expansions in quantum electrodynamics and related field theories. The method is based on a nonlinear sequence transformation and uses as input data only the numerical values of a finite number of perturbative coefficients. The results obtained in this way are for alternating series superior to those obtained using Padé approximants. The nonlinear sequence transformation fulfills an accuracy-through-order relation and can be used to predict perturbative coefficients. In many cases, these predictions are closer to available analytic results than predictions obtained using the Padé method.