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Precision measurements of the timelike electromagnetic form factors of pion, kaon, and proton.

The CLEO collaboration
Pedlar, T.K. , Cronin-Hennessy, D. , Gao, K.Y. , Gong, D.T. , Hietala, J. , Kubota, Y. , Klein, T. , Lang, B.W. , Li, S.Z. , Poling, R.
Phys.Rev.Lett. 95 (2005) 261803, 2005.
https://doi.org/10.17182/hepdata.130708

Abstract (data abstract)
A precise measurement of the cross section of the process $e^+e^- \to \pi^+\pi^-(\gamma)$ 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 $e^+e^-\to\mu^+\mu^-(\gamma)\gamma_{\rm ISR}$, 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 $1.8$ GeV is $(514.1 \pm 2.2({\rm stat}) \pm 3.1({\rm syst}))\times 10^{-10}$.

  • Born cross-section

    Data from Table 1

    10.17182/hepdata.130708.v1/t1

    Born cross section of $e^+e^-\rightarrow h^+h^-$

  • Timelike form factor

    Data from Table 1

    10.17182/hepdata.130708.v1/t2

    Timelike form factor

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