Trilinear Gauge Boson Couplings in the MSSM

Abstract We study the C and P even WWγ and WWZ trilinear gauge boson vertices (TGV's), in the context of the MSSM assuming that the external W 's are on their mass shell. We find that for energies s  q 2 ⩽ 200 GeV squark and slepton contributions to the aforementioned couplings are two orders of magnitude smaller than those of the Standard Model (SM). In the same energy range the bulk of the supersymmetric Higgs corrections to the TGV's is due to the lightest neutral Higgs, h 0 , whose contribution is like that of a Standard Model Higgs of the same mass. The contributions of the neutralinos and charginos are sensitive to the input value for the soft gaugino mass M 1 2 , being more pronounced for values M 1 2 GeV . In this case and in the unphysical region, 0 s W , their contributions are substantially enhanced resulting in large corrections to the static quantities of the W boson. However, such an enhancement is not observed in the physical region. In general for 2M W s GeV the MSSM predictions differ from those of the SM but they are of the same order of magnitude. To be detectable deviations from the SM require sensitivities reaching the per mille level and hence unlikely to be observed at LEP200. For higher energies SM and MSSM predictions exhibit a fast fall-off behaviour, in accord with unitarity requirements, getting smaller, in most cases, by almost an order of magnitude already at energies s ≈ 0.5 TeV.