Supersymmetric world from a conservative viewpoint
Wednesday, May 24, 2006
New values of "g" and the fine-structure constant
Gerry Gabrielse, an experimenter from Harvard University, and his collaborators are going to announce new, more accurate values of the fundamental constants. Using their single-electron quantum cyclotron, they can see that the new magnetic moment of the electron is
g/2 = 1.001 159 652 180 85 (76).
As you can see, there are 13 significant figures or so - the value is six times more accurate than ever before. Using the cyclotron result for "g" above plus QED theorists from other universities, they can also deduce the value of the fine-structure constant. The theoretical calculation, starting with the terms
g/2 = 1 + alpha / 2 pi,
requires to calculate 891 diagrams with up to four loops, and the result for the fine-structure constant
1 / alpha = 137.035 999 710 (96)
is ten times more accurate than the results from atom-recoil measurements. In fact, it is the first improvement of the accuracy in roughly 20 years. The precise value is sensitive on new physics at 130 GeV. All skillful numerologists are welcome to interpret the new data.
Update: Thanks to Alejandro Rivero: the correct sequence in 1/alpha is indeed "999" instead of the previous typo "997".