1998/09/10 by X. Y. Pham, Pham, X. Y.
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #hep-ph
paper · pdf · doi:10.48550/arxiv.hep-ph/9809322
5 LaTeX pages (text) + 1 postscript page for the figures
arxiv created 1998/09/10 · arxiv updated 2009/11/30
Neutrino oscillations as suggested by the recent Super-Kamiokande result imply that lepton numbers could be violated, and Z→ μ∓ +τ± is a typical manifestation. We point out that for this mode, the GIM cancelation is much milder with only a logarithmic behavior log (m3 /m2) where mj is the neutrino mass. The ratio Γ(Z → μ∓ + τ±)/Γ(Z → μ- + μ+) could be about 10-5-10-6, in sharp contrast with the vanishingly small rate τ±→ μ± + γ strongly suppressed by a quadratic power (m32-m22)/ M\rm W2. Being complementary to neutrino oscillation experiments, measurements of Z→ μ∓ +τ± -- which are at hand with the present colliders -- would give one more constraint to the lepton mixing angle sin 2θjk and the neutrino mass ratio mj/mk.