298 articles – 2332 references  [version française]
 HAL: in2p3-00697175, version 1
 arXiv: 1205.2228
 Physical Review D 86 (2012) 032013
 Precise Measurement of the e+ e- --> pi+ pi- (gamma) Cross Section with the Initial-State Radiation Method at BABAR
 J. P. Lees1, V. Poireau1, V. Tisserand1, D. Bernard2, M. Verderi2, N. Arnaud3, M. Davier3, D. Derkach3, G. Grosdidier3, F. Le Diberder3, A. M. Lutz3, B. Malaescu3, P. Roudeau3, M. H. Schune3, A. Stocchi3, L. L. Wang3, G. Wormser3, S. Akar4, E. Ben-Haim4, M. Bomben4, G. R. Bonneaud4, H. Briand4, G. Calderini4, J. Chauveau4, O. Hamon4, Ph. Leruste4, G. Marchiori4, J. Ocariz4, S. Sitt4, S. Emery5, G. Hamel de Monchenault5, G. Vasseur5, Ch. Yeche5
 For the BABAR collaboration(s)
 (2012)
 A precise measurement of the cross section of the process $e^+e^-\to\pi^+\pi^-(\gamma)$ from threshold to an energy of 3GeV is obtained with the initial-state radiation (ISR) method using $232\invfb$ of data collected with the BaBar detector at $e^+e^-$ center-of-mass energies near 10.6GeV. The ISR luminosity is determined from a study of the leptonic process $e^+e^-\to\mu^+\mu^-(\gamma)\gamma_{\rm ISR}$, which is found to agree with the next-to-leading-order QED prediction to within 1.1%. The cross section for the process $e^+e^-\to\pi^+\pi^-(\gamma)$ is obtained with a systematic uncertainty of 0.5% in the dominant $\rho$ resonance region. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the measured $\pi\pi$ cross section from threshold to 1.8GeV is $(514.1 \pm 2.2({\rm stat}) \pm 3.1({\rm syst}))\times 10^{-10}$.
 Subject(s) : Physics/High Energy Physics - Experiment