R.G. Ellis

Hard gamma emission from b-decay and the Higgs boson doublet model

Abstract The possible contribution to b→ s + γ decay of the charged physical Higgs boson is discussed in models with two Higgs boson doublets. It is shown that the extra charged Higgs boson exchange in the one-loop level significantly enhance the b→ s+ γ decay over the standard theory which has one Higgs boson doublet. The possible detection of hard gamma from b→ s+ γ decay through ϒ‴ in the e + e − annihilation experiments will give rigorous restrictions on the possibility of two Higgs boson doublet models The b→ s+ γ decay is also briefly discussed.

A one-loop renormalization group analysis of the Gelmini-Roncadelli model

Abstract A one-loop renormalization group analysis is presented of the Gelmini-Roncadelli model of neutrino mass generation via an extended Higgs sector. We are unable to find values for the quartic scalar couplings at the W mass scale which cause the combined Higgs-gauge couplings to evolve to a stable fixed point of the renormalization group. As a consequuence this model may well be “trivial” in the same sense as λφ 4 theory is believed to be in four dimensions.

Bremsstrahlung and neutral currents

The utility of the bremsstrahlung process in detecting parity violations from V-A weak neutral current interference is analysed in two ways. Firstly, bremsstrahlung from polarised-lepton-nucleus scattering has an asymmetry with respect to the polarisation of the incident leptons and, secondly, bremsstrahlung from unpolarised-lepton-nucleus scattering has a small circular polarisation. The magnitude of each effect is calculated. The ratio of the parity-violating contribution and the parity-conserving contribution to the cross section is shown to be a misleading measure of the utility of these experiments. A parameter, the figure of merit, is introduced and used to discuss the feasibility of possible experiments.

Muon-electron scattering and neutral currents

An analysis is made of the utility of muon-electron scattering as a process for detecting parity violations from the interference between the electromagnetic and weak neutral currents. The scattered electron cross section has an asymmetry with respect to the polarisation of the incident muon. The kinematics are optimised to maximise this effect, therefore giving the minimum number of muons required to achieve a statistically significant asymmetry. With muons of energy 270 GeV this number is about 9*1012.

Electromagnetic decay widths for L=1, J/sup P/C=1/sup - -/ T baryonia

A mass spectrum for the J/sup P/C=1/sup - -/, L=1, T baryonium states in the 1--5 GeV region is presented within the framework of quantum chromodynamics. The potential-dependent coefficients are determined from known baryons and mesons. The electromagnetic decay widths are calculated for these states by extension of the Van Royen--Weisskopf technique.

Electromagnetic decay widths for L = 1 , J PC = 1 − − T baryonia

A mass spectrum for the J/sup P/C=1/sup - -/, L=1, T baryonium states in the 1--5 GeV region is presented within the framework of quantum chromodynamics. The potential-dependent coefficients are determined from known baryons and mesons. The electromagnetic decay widths are calculated for these states by extension of the Van Royen--Weisskopf technique.