Measurement of $\sigma(e^+e^-\to\pi^+\pi^-\gamma(\gamma))$ and the dipion contribution to the muon anomaly with the KLOE detector

The KLOE collaboration Ambrosino, F. ; Antonelli, A. ; Antonelli, M. ; et al.
Phys.Lett.B 670 (2009) 285-291, 2009.
Inspire Record 797438 DOI 10.17182/hepdata.57088

We have measured the cross section $\sigma(e^+e^-\to\pi^+\pi^-\gamma(\gamma))$ at DA$\Phi$NE, the Frascati \phi-factory, using events with initial state radiation photons emitted at small angle and inclusive of final state radiation. We present the analysis of a new data set corresponding to an integrated luminosity of 240 pb$^{-1}$. We have achieved a reduced systematic uncertainty with respect to previously published KLOE results. From the cross section we obtain the pion form factor and the contribution to the muon magnetic anomaly from two pion states in the mass range $0.592 < M_{\pi\pi} < 0.975$ GeV. For the latter we find $\Delta a^{\pi\pi}_\mu = (387.2\pm0.5_{\rm stat}\pm2.4_{\rm exp}\pm2.3_{\rm th})\times 10^{-10}$

3 data tables

Differential cross section for E+ E- --> PI+ PI- GAMMA (GAMMA).

Total cross section for E+ E- --> PI+ PI-.

Pion form factor.


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.