Proton structure effects in muonic hydrogen
Carl Carlson (William and Mary College)

A discrepancy between the proton charge radius recently measured using muonic hydrogen and earlier measurements from electron scattering and from energy shifts in electronic hydrogen motivate a reconsideration of all calculated proton structure contributions to the Lamb shift. We will briefly review the discrepancy and the known theoretical work, comment on possible explanations from exotic physics, and then present a specific reconsideration of the two- photon contributions to the muonic Lamb shift. Our new results differ noticeably from the existing literature, although not nearly by enough to explain the charge radius discrepancy.