  We propose to use atmospheric neutrinos as a powerful probe of new physics
beyond the Standard Model via neutrino trident production. The final state with
double muon tracks simultaneously produced from the same vertex is a
distinctive signal at large Cherenkov detectors. We calculate the expected
event numbers of trident production in the Standard Model. To illustrate the
potential of this process to probe new physics we obtain the sensitivity on new
vector/scalar bosons with coupling to muon and tau neutrinos.
