Hadronic cross section measurements and contribution to $(g-2)_\mu$ with KLOE

TL;DR

This paper reports a precise measurement of the pion form factor by the KLOE experiment, refining the contribution to the muon anomalous magnetic moment and confirming existing discrepancies with the Standard Model.

Contribution

It presents a new, more precise measurement of the pion form factor and its contribution to $(g-2)_rac{2}{rac{2}}$, improving the accuracy over previous results.

Findings

Smaller statistical and systematic errors in the new measurement.

Results are consistent with previous KLOE measurements.

Confirms the discrepancy between Standard Model prediction and experimental value of rac{g-2}{rac{2}}.

Abstract

The KLOE experiment at the DA$\Phi$NE $\phi$-factory has performed a new precise measurement of the pion form factor using Initial State Radiation events. Results based on an integrated luminosity of 240 pb$^{-1}$ and extraction of the $\pi\pi$ contribution to $a_\mu$ in the mass range $0.35< M^2_{\pi\pi}<0.95$ GeV$^2$ are presented. The new value of $a^{\pi\pi}_\mu$ has smaller statistical and systematic error and is consistent with the KLOE published value (confirming the current disagreement between the Standard Model prediction for $a_\mu$ and the measured value).