Nature of the Darwin term and (Zα ) 4 m 3 / M 2 contribution to the Lamb shift for an arbitrary spin of the nucleus
Abstract
The contact Darwin term is demonstrated to be of the same origin as the spin-orbit interaction. The
(Zα
)
4
m
3
/
M
2
correction to the Lamb shift, generated by the Darwin term, is found for an arbitrary nonvanishing spin of the nucleus, both half-integer and integer. There is also a contribution of the same nature to the nuclear quadrupole moment.