Search for right-handed currents in the decay chain of K(sup +) (yields) (mu)(sup +)(nu)(sub (mu)), (mu)(sup +) (yields) e(sup +)(nu)(sub e)(nu)-bar(sub (mu))

摘要

The asymmetry of positrons in the K(sup +) yields (mu)(sup +)(nu), (mu)(sup +) yields e(sup +)(nu)(sub e)(nu)-bar(sub (mu)) decay chain was measured in a search for right-handed weak currents in (Delta)S = 1 semi-leptonic decay. High-intensity low-background monoenergetic polarized muons of 236 MeV/c momentum resulting from kaon decay at rest were directly extracted from a primary production target which was hit by a proton beam of the KEK 12-GeV proton synchrotron. Muons were stopped in a pure-aluminum plate, and the energy-integrated asymmetry of the decay positrons with respect to the incoming muon direction was determined to high precision. The observed asymmetry yielded (xi)P(sub (mu)) = -0.9996 (+-) 0.0030(stat) (+-) 0.0048(sys). This result revealed no evidence of right-handed currents in this kaon-decay chain, and set a stringent bound on the mass of the right-handed weak boson. (author) 52 refs. (ERA citation 19:022825)