Consequences of a possible gamma gamma resonance at KEK TRISTAN.

Abstract

If high mass $\ensuremath{\gamma}\ensuremath{\gamma}$ events observed at CERN LEP are due to the production of a $\ensuremath{\gamma}\ensuremath{\gamma}$ resonance via its leptonic coupling, its consequences can be observed at KEK TRISTAN. We find that a predicted $Z$ decay branching rate is too small to account for the observed events if the resonance spin is zero, due to a strong cancellation in the decay amplitudes. Such a cancellation is absent if the resonance has a spin two. We study the consequences of a tensor production in the processes ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}, {\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}, \mathrm{and} \ensuremath{\gamma}\ensuremath{\gamma}$ at energies reached at TRISTAN. Complete helicity amplitudes with tensor boson exchange contributions are given, and the signal can clearly be identified from various distributions. TRISTAN experiments are also sensitive to the virtual tensor boson exchange effects, which reduce to the contact interaction terms in the high mass limit.