Resonant bound state production at e−e− colliders

Observation of a sequence of resonances at an e−e− collider would suggest bound states of strongly coupled constituents carrying lepton number. Obvious candidates for these exotic constituents are leptoquarks and leptogluons. We show that under reasonable assumptions, the existence of one leptogluon flavor of appropriate mass can give rise to sizable “leptoglueball” production rates and observable resonance peaks. In contrast, one needs two leptoquark flavors in order to produce the analogous “leptoquarkonium” states. Moreover, cross-generational leptoquark couplings are necessary to give observable event rates in many cases, and leptoquarkonium mass splittings are too small to resolve with realistic beam energy resolutions.