Speaker
Description
The measurement of exclusive $e^+e^−$ to hadrons processes is a significant part of the physics program of the $BABAR$ experiment, aimed to improve the calculation of the hadronic contribution to the muon $g−2$ and to study the intermediate dynamics of the processes. We present the most recent studies performed on the full data set of about 470 ${\mathrm {fb}}^{−1}$ collected at the PEP-II $e^+e^−$ collider at a center-of-mass energy of about 10.6 GeV.
In particular, we report the results on $e^+e^−$ annihilation into three pions in an energy range from production threshold up to about 4 GeV. From the fit to the measured $3\pi$ mass spectrum we determine the products $\Gamma(V\to e^+e^-){\cal{B}}(V\to 3\pi)$ for the $\omega$ and $\phi$ resonances, and ${\cal{B}}(\rho\to 3\pi)$. The latter isospin-breaking decay is observed with 6 sigma significance. The measured $e^+e^- \to \pi^+\pi^-\pi^0$ cross section is used to calculate the leading-order hadronic contribution to the muon magnetic anomaly from this exclusive final state with significant improved accuracy.
We also present a measurement of the cross section for three $e^+e^- \to 2K\,3\pi$ processes, together with the study of the many intermediate states. In particular we find hints for a new possible decay of the recently discovered $\phi(2170)$ resonant state.
| Submitted on behalf of a Collaboration? | Yes |
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