Recent BABAR results on measurement of exclusive hadronic cross sections

TL;DR

This paper presents recent BABAR measurements of exclusive hadronic cross sections, including six- and seven-pion final states and kaon pair production, to improve the understanding of the muon g-2 and intermediate hadronic dynamics.

Contribution

It provides new measurements of specific hadronic cross sections and investigates resonance states around 2.2 GeV, enhancing the precision of hadronic contributions to muon g-2.

Findings

Measured $e^+e^-$ to six- and seven-pion cross sections.

Supported the existence of the $ ho(2230)$ resonance.

Improved understanding of the discrepancy between QCD predictions and observed cross sections.

Abstract

The measurement of exclusive $e^+e^-$ to hadrons processes is a significant part of the physics program of $BABAR$ 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 results obtained by using the full data set of about 470\,fb$^{-1}$ collected by the BABAR detector 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 six- and seven-pion final states. The study of the very rich dynamics of these processes can help to understand the difference seen between the QCD prediction and the sum of exclusive cross sections in the energy region around 2 GeV, thus improving the precision on the total hadronic cross section and of the $g-2$ calculation. Additionally, we report the results on a dedicated study to shed light on the resonant states production in the energy region around 2.2 GeV, which is presently rather unclear. We measure the reaction $e^+e^-\to K_SK_L$ with data collected with the $BABAR$ detector and analyse these data in conjunction with published BESIII data on $e^+e^-\to K^+K^-$ and $BABAR$ data on $e^+e^-\to K^+K^-$, $\pi^+\pi^-$, $\pi^+\pi^-\eta$, $\pi^+\pi^-\omega$. This study supports the existence of an isovector resonance $\rho(2230)$ consistent with the resonance observed by BESIII.