INVERSE MUON DECAY IN A MAGNETIC-FIELD - POLARIZATION EFFECTS

The cross section for the production of a high-energy muon in the scat tering of a low-energy (anti)neutrino by an ultrarelativistic electron (v(mu) + e(-) --> mu(-) + v(e) and <(v)over bar (e)> + e(-) --> mu(-) + <(v)over bar (mu)>) in a constant uniform magnetic field is calcula ted with allowance for the transverse and longitudinal polarizations o f the electron and muon. The asymptotic behavior of the cross sections as functions of the kinematical and field parameters is studied. it i s shown that muons produced in the v(mu) process are polarized predomi nantly in the direction opposite to that of the magnetic field. This p rocess is forbidden for electrons having a right-hand circular polariz ation, Only muons having a left-hand circular polarization are produce d in the <(v)over bar (e)> process. For transversely polarized electro ns, the cross section is larger when their spins are oriented along th e field. The effect of a weak field is mole pronounced for transversel y polarized particles than for longitudinally polarized ones; it becom es especially significant near the threshold or free processes. In a s trong field, only muons and electrons having left-hand circular polari zations are involved in the processes in question.