Вы находитесь на старом сайте НГУ. Перейти на новый сайт

ISSN - 14346044, EISSN - 14346052, European Physical Journal C, 2003, vol. 31, p. 503-510

Updated estimate of the muon magnetic moment using revised results from e+e- annihilation

Davier M., Eidelman S., Höcker A., Zhang Z.

A new evaluation of the hadronic vacuum polarization contribution to the muon magnetic moment is presented. We take into account the reanalysis of the low-energy e+e- annihilation cross section into hadrons by the CMD-2 Collaboration. The agreement between e+e- and τ spectral functions in the ππ channel is found to be much improved. Nevertheless, significant discrepancies remain in the center-of-mass energy range between 0.85 and 1.0 GeV, so that we refrain from averaging the two data sets. The values found for the lowest-order hadronic vacuum polarization contributions are aμ had,LO = {(696.3 ± 6.2exp ± 3.6rad) 10-10 [e +e--based], (711.0 ± 5.0exp ± 0.8rad ± 2.8SU(2)) 10-10 [τ-based], where the errors have been separated according to their sources: experimental, missing radiative corrections in e+e- data, and isospin breaking. The corresponding Standard Model predictions for the muon magnetic anomaly read aμ = {(11 659 180.9 ± 7.2had ± 3.5LBL ± 0.4QED+EW) 10-10 [e+e--based], (11 659 195.6 ± 5.8had ± 3.5LBL ± 0.4QED+EW) 10-10 [τ-based], where the errors account for the hadronic, light-by-light (LBL) scattering and electroweak contributions. The deviations from the measurement at BNL are found to be (22.1 ± 7.2 ± 3.5 ± 8.0) 10 -10 (1.9 σ) and (7.4 ± 5.8 ± 3.5 ± 8.0) 10-10 (0.7 σ) for the e+e-- and τ-based estimates, respectively, where the second error is from the LBL contribution and the third one from the BNL measurement.