Laboratoire d'Annecy-le-Vieux de Physique des Particules (LAPP), Université de Savoie, CNRS/IN2P3, F-74941 Annecy-Le-Vieux, France.
Phys Rev Lett. 2009 Dec 4;103(23):231801. doi: 10.1103/PhysRevLett.103.231801. Epub 2009 Dec 3.
A precise measurement of the cross section of the process e(+)e(-) --> pi(+)pi(-)(gamma) from threshold to an energy of 3 GeV is obtained with the initial state radiation (ISR) method using 232 fb(-1) of data collected with the BABAR detector at e(+)e(-) center-of-mass energies near 10.6 GeV. The ISR luminosity is determined from a study of the leptonic process e(+)e(-) --> mu(+)mu(-)gamma(gamma). The leading-order hadronic contribution to the muon magnetic anomaly calculated using the pipi cross section measured from threshold to 1.8 GeV is (514.1 +/- 2.2(stat) +/- 3.1(syst)) x 10(-10).
使用 BABAR 探测器在接近 10.6 GeV 的质心系能量下收集了 232 fb-1 的数据，采用初始态辐射（ISR）方法对阈值到 3 GeV 能区的过程 e(+)e(-) --> pi(+)pi(-)(gamma)的截面进行了精确测量。通过对电子-正电子对(e+)e(-) --> mu(+)mu(-)gamma(gamma)的研究，确定了 ISR 亮度。使用从阈值到 1.8 GeV 测量的 pipi 截面计算的 muon 磁反常的领头阶强子贡献为 (514.1 +/- 2.2(stat) +/- 3.1(syst)) x 10(-10)。
