Brodsky et al. Reply:

A Reply to the Comment by J. L. Friar and I. Sick.

Figure 1

The Zemach radius $⟨r{⟩}_Z$ vs the rms value of the electric charge radius $\sqrt{⟨r_E^2⟩}$ for several form factor models, as listed in Ref. 1. The horizontal lines correspond to the value and range for $⟨r{⟩}_Z=1.043(16)\mathrm{fm}$ obtained from the hydrogen and muonium HFS comparison. The filled circle reflects the results given in Ref. 5 from electron-proton scattering.