Lorentz structure of weak current in ν interactions and inverse muon decay

Neutrino interactions uniquely convey the Lorentz structure of weak current. Two studies that probe this structure are reviewed: structure functions from anti νμ- and νμ-induced charged current events; and the inverse muon decay process, νμ+e- → μ- + νe. In the first study, the relative absence of anti νμ-induced charged current events with respect to νμ-induced events at large z (> 0.45) and large y (> 0.70) (investigated by CDHS and CCFR) restricts vertical strokeηvertical stroke2 = vertical strokegR/gLvertical stroke2 < 0.0015 with 90% CL (CCFR). Within the framework of left-right symmetric models, this measurement imposes a limit upon the mixing angle of the left and right handed bosons. Unlike the limits imposed by the μ-decay and the nuclear β-decay experiments, the present limit is valid irrespective of the mass of the right handed neutrino. In the second study, recent high statistics measurements of inverse muon decay by CCFR and CHARM II yield a total cross section, σ(νμ + e- → μ- + νe) = (17.3 ± 0.72stat) ± 0.39 (syst)]Eν10-42 cm2/GeV. This restricts the solar coupling of the muon vertical strokegLLsvertical stroke < 0.25 with 90% CL. (orig.)