Two new low-energy theorems for Compton scattering from spin-½ targets, giving some terms of order ${\omega }^2$, are derived using a recently obtained lemma. One of these theorems is a generalization to the spin-½ case of a similar theorem for the spin-0 case. The other theorem involves "magnetic moment radius," i.e., ${\left[\frac{d{G}_M\mathrm{}\left(t\right)\mathrm{}}{\mathrm{dt}}\right]}_{t=0\mathrm{}}$, which does not occur in any of the low-energy theorems obtained earlier.

• Received 30 August 1967

DOI:https://doi.org/10.1103/PhysRev.165.1532