Speaker
Description
Photon-photon interactions provide a clean probe of hadron structure, resonance dynamics, and precision QCD observables. In my talk, I will give a broad overview of the phenomenology of real and virtual two-photon processes, with emphasis on recent progress based on analyticity, unitarity, and dispersion relations. I will discuss dispersive descriptions of $\gamma^{(*)}\gamma^{(*)} \to \pi\pi/K\bar{K}$ and $\gamma^{(*)}\gamma^{(*)} \to \pi\eta / K\bar{K}$, the emergence of scalar and tensor resonances, and the connection to pion polarizabilities and hadronic light-by-light scattering in the muon $g-2$. I will also comment on our recent applications to virtual Compton scattering off the proton, where two-photon dynamics enters as input to the t-channel dispersion integrals, and on related applications to $\phi \to \pi^0 \pi^0 \gamma$, as well as on Monte Carlo tools for two-photon production at $e^+e^-$ facilities.
