Improved determination of the fine structure constant based on the electron g-2 and muonium hyperfine structure

Preliminary results of two accurate determinations of the fine structure constant /spl alpha/ based on quantum electrodynamics are reported. One is obtained from an improved evaluation of the sixth-order and eighth-order radiative corrections to the electron anomalous magnetic moment a/sub e/. This leads to the most accurate value of /spl alpha/ obtained thus far, with an uncertainty of about 0.005 part per million (ppm). The other is the outcome of an evaluation of the complete /spl alpha//sup 2/(Z/spl alpha/) contribution and the leading /spl alpha//sup 4/ and /spl alpha//sup 3/(m/sub e//m/sub /spl mu//) contributions to the hyperfine structure of the muonium ground state. This gives a value of /spl alpha/ with an uncertainty of 0.134 ppm. These results also lead to the most accurate determination of the muon mass.<
>