QED-Induced Rapidity-Gap Events at the Z Peak

Abstract

We study rapidity-gap events in $e^+e^-$ annihilation at the Z boson peak initiated by the emission of a virtual photon. This mechanism is suppressed by the QED coupling constant, but it is enhanced due to a large propagator term from the virtual photon. For typical kinematics, we find a smaller event rate than analogous QCD type gap events. In the small jet-pair invariant mass limit, the QED type events follow a $1+\cos^2\theta$ distribution in the jet-pair scattering angle, instead of the $\sin^2\theta$ distribution of the QCD case.