Fine-structure constant obtained from an improved calculation of the electron g-2

A preliminary result is presented for an accurate determination of the fine-structure constant /spl alpha/ based on an improved evaluation of the sixth- and eighth-order radiative corrections to the electron anomalous magnetic moment /spl alpha//sub e/. In combination with a very precise measurement of /spl alpha//sub e/, this leads to the most accurate value of /spl alpha/ obtained thus far, with a relative standard uncertainty of less than 4/spl times/10/sup -9/.