Calculations of the degree of parity nonconservation in the spin-rotational spectrum of the PbF molecule

Recent calculations for the PbF molecule are used to obtain the level energies of the rotational and hyperfine structures of the ground electronic–vibrational state of the molecule. The degree of parity nonconservation in magnetic-dipole transitions between these levels are also computed. It is shown that, apart from the predicted parametric enhancement of parity nonconservation in diatomic radicals, additional amplification due to details of the spectrum also occurs for some transitions. The degree of parity nonconservation may exceed 10^{– 3}. The parity nonconservation in the spin-rotational spectrum of the PbF molecule is related to the as yet unmeasured constant of a parity-nonconserving electron–nuclear neutral current and to the anapole moment of the lead nucleus.