Search for lepton flavor violation at future lepton colliders

Lepton flavor violating (LFV) processes, e(+)e(-) -> e(+)l(-) and e(-)e(-) -> e(-)l(-) (l - mu or tau), via four -Fermi contact interactions at future International Linear Collider (ILC) are studied. Taking account of previous experimental results of LFV processes it tau -> 3e and r > 3e, we find that the upper limits on the LFV parameters for l - tau could be improved at the ILC experiment using the polarized electron beam. The improvement of the upper limits could be nearly an order of magnitude as compared to previous ones.