Simple atoms, QED and proton radius puzzle

by Savely Karshenboim (MPQ Garching)

Monday 11 May 2015, 14:15 → 15:45 Europe/Berlin

3344 (TUM - Physics Department - Garching)

QED by itself cannot perfectly describe simple atoms such as ordinary or muonic hydrogen, because at a certain stage we need an adequate description of the nuclear properties as input data. Value of the proton radius is a key input parameter for the Lamb shift in ordinary and muonic hydrogen. One can use its value to check QED, or use QED to extract a value of the proton radius. At present, there are three methods to determine the proton radius. One is based on the elastic electron-proton scattering, while two others are from spectroscopy of ordinary and muonic hydrogen. Present days, the muonic value strongly disagrees with the ordinary-hydrogen one and with the scattering one. I will review the situation with determination of the proton radius, mainly focusing in spectroscopic determinations.