Probing lepton flavour violation in $ u_{mu} + N to tau + ...$ scattering and $mu to tau$ conversion on nucleons

We study lepton flavour-violating interactions which could result in the $tau$-lepton production in the $ u_{mu}N$ scattering or in $mu to tau$ conversion on nucleons at high energies. Phenomenological bounds on the strength of $bar{tau} u_{mu}bar{q}q^{}$ interactions are extracted from the combined result of the NOMAD and CHORUS experiments on searching for $ u_{mu} - u_{tau}$ oscillations. Some of these bounds supersede limits from rare decays. We also propose a ``missing energy type experiment searching for $mu - tau$ conversion on nucleons. The experiment can be performed at a present accelerator or at a future neutrino factory.