## Monday, July 23, 2018

#### [1801.08816] New measurement of the $1S-3S$ transition frequency of hydrogen: contribution to the proton charge radius puzzle
Abstract: We present a new measurement of the $1S-3S$ two-photon transition frequency of hydrogen, realized with a continuous-wave excitation laser at 205 nm on a room-temperature atomic beam, with a relative uncertainty of $9\times10^{-13}$. The proton charge radius deduced from this measurement, $r_\text{p}=0.877(13)$ fm, is in very good agreement with the current CODATA-recommended value.