Measurement of sigma(e+ e- --> pi+ pi- gamma) and extraction of sigma(e+ e- --> pi+ pi-) below 1-GeV with the KLOE detector.

The KLOE collaboration Aloisio, A. ; Ambrosino, F. ; Antonelli, A. ; et al.
Phys.Lett.B 606 (2005) 12-24, 2005.
Inspire Record 655225 DOI 10.17182/hepdata.41901

We have measured the cross section $\sigma(e^+e^-\to \pi^+\pi^- \gamma)$ at an energy $W=m_\phi=1.02$ GeV with the KLOE detector at the electron-positron collider DA$\Phi$NE. From the dependence of the cross section on the invariant mass of the two-pion system, we extract $\sigma(e^+e^-\to \pi^+\pi^-)$ for the mass range $0.35<s<0.95$ GeV$^2$. From this result, we calculate the pion form factor and the hadronic contribution to the muon anomaly, $a_\mu$.

3 data tables

The differential cross section as a function of the invariant mass of the di-pion system in the angular region THETA(PIPI) <15 DEGREES or THETA(PIPI) >165 DEGREES and THETA(PI) in the region 0 to 180 DEGREES.

The physical cross section for E+ E- --> PI+ PI- including FSR and vacuum polarization effects.

The pion form factor with FSR and vacuum polarization effects removed.