  We consider a spin-1/2 electron and a spin-1/2 nucleus interacting with the
quantized electromagnetic field in the standard model of non-relativistic QED.
For a fixed total momentum sufficiently small, we study the multiplicity of the
ground state of the reduced Hamiltonian. We prove that the coupling between the
spins of the charged particles and the electromagnetic field splits the
degeneracy of the ground state.
