Light-by-light scattering sum rules in light of new data

Igor Danilkin (Mainz)

We evaluate the light-quark meson contributions to three exact light-by-light scattering sum rules in light of new data by the Belle Collaboration, which recently has extracted the transition form factors of the tensor meson f₂(1270) as well as of the scalar meson f₀(980). We confirm a previous finding that the η, η′ and helicity-2 f₂(1270) contributions saturate one of these sum rules up to photon virtualities up to around 1 GeV². At larger virtualities, our sum rule analysis shows an important contribution of the f₂(1565) meson and provides a first empirical extraction of its helicitiy-2 transition form factor. Two further sum rules allow us to predict the helicity-0 and helicity-1 transition form factors of the f₂(1270) meson. Furthermore, our analysis also provides an update for the scalar and tensor meson hadronic light-by-light contributions to the muon's anomalous magnetic moment.  

Seminarraum II