The use of genetic algorithms to maximize the performance of a partially lined screened room

This paper shows that it is possible to use genetic algorithms to optimize the layout of ferrite tile absorber in a partially lined screened enclosure to produce a "best" performance. The enclosure and absorber are modeled using TLM modeling techniques and the performance is determined by comparison with theoretical normalized site attenuation of free space. The results show that it is possible to cover just 80% of the surface of the enclosure with ferrite absorber and obtain a response which is within +/-4 dB of the free space response between 40 and 200 MHz

Bessel processes, the Brownian snake and super-Brownian motion

We prove that, both for the Brownian snake and for super-Brownian motion in dimension one, the historical path corresponding to the minimal spatial position is a Bessel process of dimension -5. We also discuss a spine decomposition for the Brownian snake conditioned on the minimizing path.Comment: Submitted to the special volume of S\'eminaire de Probabilit\'es in memory of Marc Yo

SUSY QCD Corrections to Higgs-b Production : Is the \Delta_b Approximation Accurate?

The associated production of a Higgs boson with a b quark is a discovery channel for the lightest MSSM neutral Higgs boson. We consider the SUSY QCD contributions from squarks and gluinos and discuss the decoupling properties of these effects. A detailed comparison of our exact order(alpha_s) results with those of a widely used effective Lagrangian approach, the \Delta_b approximation, is presented. The \Delta_b approximation is shown to accurately reproduce the exact one-loop SQCD result to within a few percent over a wide range of parameter space.Comment: figures added, version to be published in Phys Rev

Supersymmetric approximations to the 3D supersymmetric O(N) model

We develop several non-perturbative approximations for studying the dynamics of a supersymmetric O(N) model which preserve supersymmetry. We study the phase structure of the vacuum in both the leading order in large-N approximation as well as in the Hartree approximation, and derive the finite temperature renormalized effective potential. We derive the exact Schwinger-Dyson equations for the superfield Green functions and develop the machinery for going beyond the next to leading order in large-N approximation using a truncation of these equations which can also be derived from a two-particle irreducible effective action.Comment: 16 pages, 3 figure

Improved Plane-Wave Illumination for TLM Method

An efficient solution to the problems associated with plane wave illumination of a scattering body in a TLM mesh is presented. The solution is equivalent to a partial implementation of the Huygens surface [1] used in the time-domain finite difference (TDFD) method, but, additionally, accounts for dispersion effects