Revised value of the eighth-order electron g-2

The contribution to the eighth-order anomalous magnetic moment (g-2) of the electron from a set of diagrams without closed lepton loops is recalculated using a new FORTRAN code generated by an automatic code generator. Comparing the contributions of individual diagrams of old and new calculations, we found an inconsistency in the old treatment of infrared subtraction terms in two diagrams. Correcting this error leads to the revised value -1.9144 (35) (alpha/pi)^4 for the eighth-order term. This theoretical change induces the shift of the inverse of the fine structure constant by -6.41180(73)x10^{-7}.Comment: 4 pages, 1 figure, typo is correcte

Precise mass-dependent QED contributions to leptonic g-2 at order alpha^2 and alpha^3

Improved values for the two- and three-loop mass-dependent QED contributions to the anomalous magnetic moments of the electron, muon, and tau lepton are presented. The Standard Model prediction for the electron (g-2) is compared with its most precise recent measurement, providing a value of the fine-structure constant in agreement with a recently published determination. For the tau lepton, differences with previously published results are found and discussed. An updated value of the fine-structure constant is presented in "Note added after publication."Comment: 6 pages, 1 figure. v2: New determination of alpha presented (based on the recent electron g-2 measurement). v3: New formulae added in Sec.IIB. v4: Updated value of alpha presente

Eighth-Order Vacuum-Polarization Function Formed by Two Light-by-Light-Scattering Diagrams and its Contribution to the Tenth-Order Electron g-2

We have evaluated the contribution to the anomalous magnetic moment of the electron from six tenth-order Feynman diagrams which contain eighth-order vacuum-polarization function formed by two light-by-light scattering diagrams connected by three photons. The integrals are constructed by two different methods. In the first method the subtractive counter terms are used to deal with ultraviolet (UV) singularities together with the requirement of gauge-invariance. In the second method, the Ward-Takahashi identity is applied to the light-by-light scattering amplitudes to eliminate UV singularities. Numerical evaluation confirms that the two methods are consistent with each other within their numerical uncertainties. Combining the two results statistically and adding small contribution from the muons and/or tau leptons, we obtain $0.000 399 9 (18) (\alpha/\pi)^5$. We also evaluated the contribution to the muon $g-2$ from the same set of diagrams and found $-1.263 44 (14) (\alpha/\pi)^5$.Comment: 27 page

Percolative behavior of an anisotropic two-dimensional network: Growth of tellurium onto an oriented polymer film

6 págs.; 9 figs.In situ transport measurements during the growth of a thin layer of thermally evaporated tellurium onto an oriented polymer film are presented. The system, which resembles the characteristics of a two-dimensional anisotropic network, is analyzed in terms of the current percolation theory. Parameters such as the percolation threshold and the critical exponents are calculated for the perpendicular and the parallel orientation. Within the limits of the experiments the values of t∥ and t⊥ are estimated to be 1.15 and 1.46, respectively. ©1997 American Physical SocietyFinancial support by the Volkswagen Foundation and Comision Interministrial de Ciencia y Tecnologia (Grant No. MAT94-0825) are gratefully acknowledged.Peer Reviewe

Growth, micro-structuring, spectroscopy, and optical gain in as-deposited Al2O3:ErAl_2O_3:Er waveguides

Deposition and micro-structuring of $Al_2O_3:Er$ layers with low background losses (0.11 dB/cm) and lifetimes up to 7 ms have been optimized for active devices. Net gain of 0.7 dB/cm at 1533 nm has been measured.\ud \u

What happens during a blackout: Consequences of a prolonged and wide-ranging power outage

Power outages in Europe and North America in recent years have given a lasting impression of the vulnerability of modern and high-tech societies. Although the power supply was interrupted for a week at most and only locally, massive functional and supply disruptions, threats to public order and damage amounting to billions of euros have already become apparent. This book shows what consequences a prolonged and widespread power blackout could have on society and its critical infrastructures and how Germany is prepared for such a large-scale disaster. By means of comprehensive consequence analyses, the authors drastically demonstrate that after only a few days, the supply of the population with (vital) goods and services can no longer be guaranteed in the affected area. It is also made clear that considerable efforts are required to increase the sustainability of critical infrastructures and to further optimise the capacities of the national disaster management system. The book is based on TAB Report Nr. 141 "Gefährdung und Verletzbarkeit moderner Gesellschaften - am Beispiel eines großräumigen und langandauernden Ausfalls der Stromversorgung"