The Analytical Contribution of Some Eighth-Order Graphs Containing Vacuum Polarization Insertions to the Muon (G-2) in QED

The contributions to the $g-2$ of the muon from some eighth-order (four-loop) graphs containing one-loop and two-loop vacuum polarization insertions have been evaluated analytically in QED perturbation theory, expanding the results in the ratio of the electron to muon mass ${(m_e / m_\mu)}$. The results agree with the numerical evaluations and the asymptotic analytical results already existing in the literature.Comment: plain TEX, 10 pages + 3 figures (figures are available upon request), DFUB 93-0

Asymptotics of Feynman Diagrams and The Mellin-Barnes Representation

It is shown that the integral representation of Feynman diagrams in terms of the traditional Feynman parameters, when combined with properties of the Mellin--Barnes representation and the so called {\it converse mapping theorem}, provide a very simple and efficient way to obtain the analytic asymptotic behaviours in both the large and small ratios of mass scales.Comment: References added. This is the version published in Physics Letters

Atomic beam correlations and the quantum state of the micromaser

Correlation measurements on the states of two-level atoms having passed through a micromaser at different times can be used to infer properties of the quantum state of the radiation field in the cavity. Long(short) correlation length in time is to some extent associated with super(sub)-Poissonian photon statistics. The correlation length is also an indicator of a phase structure much richer than what is revealed by the usual single-time observables, like the atomic inversion or the Mandel quality factor. In realistic experimental situations the correlations may extend over many times the decay time of the cavity. Our assertions are verified by comparing theoretical calculations with a high-precision Monte-Carlo simulation of the micromaser system.Comment: 4 pages, styles: aps, latex, times, epsf, More physical insight added, title and figures changed, more references. The paper can be retrieved as compressed file called elmfors.maser.ps.Z from http://connect.nbi.dk/pub/lautrup/ or via anonymous ftp at ftp://connect.nbi.dk/pub/lautrup

The stability of solitons in biomembranes and nerves

We examine the stability of a class of solitons, obtained from a generalization of the Boussinesq equation, which have been proposed to be relevant for pulse propagation in biomembranes and nerves. These solitons are found to be stable with respect to small amplitude fluctuations. They emerge naturally from non-solitonic initial excitations and are robust in the presence of dissipation.Comment: 7 pages, 5 figure

Comment: Citation Statistics

We discuss the paper "Citation Statistics" by the Joint Committee on Quantitative Assessment of Research [arXiv:0910.3529]. In particular, we focus on a necessary feature of "good" measures for ranking scientific authors: that good measures must able to accurately distinguish between authors.Comment: Published in at http://dx.doi.org/10.1214/09-STS285B the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

On the gauge parameter dependence of QED

The gauge parameter dependence of QED in the covariant gauge can be determined explicitly by introducing a Stueckelberg field, which is a non-interacting fictitious Goldstone boson field. Examples of QED with electrons or charged scalars are discussed. Our results generalize the long known results on the gauge parameter dependence of the wave function renormalization constant and the electron propagator.Comment: 8 pages, no figure, LaTeX 2

Recent Results in Scalar QED

In this talk we present some recent and new results on the phase structure and the continuum limit of lattice formulation of pure gauge QED coupled to Higgs fields. We show the presence of second order phase transition lines allowing for a continuum limit. Nevertheless, finite size analysis shows that this theory is logarithmically trivial. The role of magnetic monopoles is also shown.Comment: PS file with figures included, 3 pag., Pre-UAB-FT-330 (to appear in the Lattice93 Proceedings