Searching for Lepton Flavor Violation at a Future High Energy Electron-Positron Collider

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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 tau -> eee, requiring the scale of the contact interaction to be less than (9 TeV)-2. We reexamine this type of physics, assuming that the particles responsible are heavy (with masses greater than 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- -> e tau 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 less than (11 TeV)-2 at collider energy sqrt(s) 500 GeV, or reaching beyond (35 TeV)-2 for sqrt(s) = 3 TeV. Even stronger bounds are possible at e-e- colliders in the same energy range.