A search for neutral Higgs bosons has been performed using the full sample of Z 0 decays collected by the OPAL detector at LEP up to 1995. The data were taken at centre-of-mass energies between 88 GeV and 95 GeV and correspond to an integrated luminosity of approximately 160 pb 1. The present search addresses the processes Z 0 !H 0 Z and h 0 Z , where H 0 is the Higgs boson predicted by the Standard Model and h 0 the lightest neutral scalar Higgs boson predicted in the framework of the Minimal Supersymmetric Standard Model. For the virtual Z 0 boson, Z , the following decay c hannels are considered: Z ! , e + e and +. One candidate event

[1] A composite model of wave propagation from terrestrial very low frequency (VLF) transmitters has been constructed to estimate the wave normal angles and fields of whistler mode waves in the plasmasphere. The model combines a simulation of the fields in the Earth-ionosphere waveguide, ionospheric absorption estimates, and geomagnetic field and plasma density models with fully three-dimensional ray tracing that includes refraction, focusing, and resonant damping. The outputs of this model are consistent with those of several previous, simpler simulations, some of which have underlying component models in common. A comparison of the model outputs to wavefield data from five satellites shows that away from the magnetic equator, all of the models systematically overestimate the median field strength in the plasmasphere owing to terrestrial VLF transmitters by about 20 dB at night and at least 10 dB during the day. In addition, wavefield estimates at L < 1.5 in the equatorial region appear to be about 15 dB too low, although measured fields there are extremely variable. Consideration of the models' similarities and differences indicates that this discrepancy originates in or below the ionosphere, where important physics (as yet not conclusively identified) is not being modeled. Adjustment of the low-altitude field estimates downward by constant factors brings the model outputs into closer agreement with satellite observations. It is concluded that past and future use of these widely employed trans-ionospheric VLF propagation models should be reevaluated.

“Peculiar” or “butterfly” electron pitch angle distributions (PADs), with minima near 90°, have recently been observed in the inner radiation belt. These electrons are traditionally treated by pure pitch angle diffusion, driven by plasmaspheric hiss, lightning‐generated whistlers, and VLF transmitter signals. Since this leads to monotonic PADs, energy diffusion by magnetosonic waves has been proposed to account for the observations. We show that the observed PADs arise readily from two‐dimensional diffusion at L = 2, with or without magnetosonic waves. It is necessary to include cross diffusion, which accounts for the relationship between pitch angle and energy changes. The distribution of flux with energy is also in good agreement with observations between 200 keV and 1 MeV, dropping to very low levels at higher energy. Thus, at this location radial diffusion may be negligible at subrelativistic as well as ultrarelativistic energy.

In a companion paper, new models of waves from ground-based very low frequency transmitters and from lightning were presented. Ray-and-power tracing provided wave amplitudes as well as trajectories and wave normal angles throughout the plasmasphere. Here, these are used to evaluate diffusion of radiation belt electrons. These are combined with recent models of hiss and Coulomb collisions to find lifetimes and particle distributions. Butterfly pitch angle distributions and near-megaelectron volt electrons are produced, confirming the role of energy diffusion. Coulomb energy drag, while often omitted, is also found to be important and should not be neglected.