Second-order corrections to correlations in muon capture

Muon capture by a nucleus with an arbitrary spin is considered. Second-orde r terms in 1/M in the effective weak-interaction Hamiltonian are taken into account. New terms in the Hamiltonian associated with the nucleon-nucleus potential are found. A general expression for the angular distribution of n eutrinos (recoil nuclei) is derived for polarized muons and oriented target nuclei. Second-order contributions to the amplitudes M-u(k) are obtained. This allows one to calculate second-order corrections to any integral and c orrelation characteristics in muon capture that are expressed in terms of M -u(k). (C) 2000 MAIK "Nauka/Interperiodica".