Two-Photon Fusion Results at BESIII

Abstract

Two-photon processes in electron-positron collisions of the form $e^{+}{e}^{-}\to e^{+}{e}^{-}X$ are a well-established tool for probing hadronic structure and provide a direct access to non-vector states in $e^{+}{e}^{-}$ collisions. Collisions of quasi real photons have been employed by several experimental collaborations to extract radiative widths of various hadronic resonances. Persistent discrepancies between Standard Model predictions and measurements of the muon anomalous magnetic moment $a_{\mu }=(g-2)\mu /2$ have renewed interest in theoretical predictions for $\gamma \gamma \to X$ processes, particularly with off-shell photons. These are essential for evaluating the hadronic light-by-light contribution to $a_{\mu }$. This work reviews results and outlines future two-photon measurements by the BESIII collaboration.

Talk presented at 59th Rencontres de Moriond QCD and High Energy Interactions (2025)