The third Zemach moment and the size of the proton

.By this way one is able to resolve the proton size puzzle [4, 5].The other attempts to resolve this puzzle, for example, to recalculate the polarizabilitycontribution [6] or to estimate the non-perturbative effect [7], and to test the possibilityof the existence of the new particle between the proton and the muon [8], have been notvery successful so far. The new corrections they have found are usually too small (The onlyexception is so-called off-mass-shell effect advocated by [9]). Therefore the simple solutionsuggested by De Ru´jula seems to be worthy of further investigation.However, the proposal of De Ru´jula has been severely criticized by several groups [10–12]. First, the toy model used by De Ru´jula has been indeed ruled out by the recentexperimental data. Furthermore, those groups have argued that such a large value of thethird Zemach moment cannot accommodate the current data of ep elastic scattering. Whatthey did, instead, is to adopt several widely used parametrizations of G