Precise Measurement of the e+ e- --> pi+ pi- (gamma) Cross Section with the Initial-State Radiation Method at BABAR
- Fonction : Auteur
- PersonId : 2078
- IdHAL : vincent-tisserand
- ORCID : 0000-0003-4916-0446
- IdRef : 188901477
- Fonction : Auteur
- PersonId : 16841
- IdHAL : nicolas-arnaud
- ORCID : 0000-0001-6589-8673
- Fonction : Auteur
- PersonId : 1444626
- IdRef : 090175859
- Fonction : Auteur
- PersonId : 1380362
- ORCID : 0000-0002-9807-861X
- IdRef : 242005462
- Fonction : Auteur
- PersonId : 10608
- IdHAL : giovanni-calderini
- ORCID : 0000-0002-9495-9145
- IdRef : 172243211
- Fonction : Auteur
- PersonId : 1508829
- IdRef : 031093507
- Fonction : Auteur
- PersonId : 741274
- IdHAL : giovanni-marchiori
- ORCID : 0000-0003-2655-7643
- IdRef : 180997203
- Fonction : Auteur
- PersonId : 745439
- IdHAL : georges-vasseur
- ORCID : 0000-0003-4009-3558
- IdRef : 139256008
Résumé
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 $(514.1 \pm 2.2({\rm stat}) \pm 3.1({\rm syst}))\times 10^{-10}$.
