UC Irvine

We consider theories where lepton flavor is violated, in particular concentrating on the four fermion operator consisting of three electrons and a tau. Strong constraints are available from existing searches for τ→eee, requiring the scale of the contact interaction to be ≲1/(9TeV)2. We reexamine this type of physics, assuming that the particles responsible are heavy (with masses ≳TeV) such that a contact interaction description continues to be applicable at the energies for a future e+e- collider. We find that the process e+e-→eτ can be a very sensitive probe of this kind of physics (even for very conservative assumptions about the detector performance), already improving upon the tau decay bounds to ≲1/(11TeV)2 at collider energy s=500GeV, or reaching ≲1/(35TeV)2 for s=3TeV. Even stronger bounds are possible at e-e- colliders in the same energy range.