Topical seminar: Dispersive analysis of two photon reactions

por Prof. Igor Danilkin (Mainz University)

jueves 25 sept. 2025 16:00 → 18:00 Europe/Madrid

1001-Primera-1-1-1 - Paterna. Seminario (Universe)

We perform a coupled-channel dispersive analysis of γ(∗)γ(∗) → {ππ, πη, KK} using a modified Muskhelishvili–Omnès framework that enforces analyticity and unitarity, modeling the left-hand cut with pion/kaon and vector-meson pole terms. Both unsubtracted and subtracted forms are studied, the latter incorporating Adler-zero constraints. The S-wave ππ/KK (I = 0) and πη/KK (I = 1) channels describe the f₀(500), f₀(980), and a₀(980), while the D-wave is anchored by the f₂(1270) and a₂(1320). As an application to (g − 2)μ, we obtain dispersive HLbL rescattering estimates from scalar channels with improved precision over narrow-width models. A new two-photon Monte Carlo generator in development at Mainz will also be briefly presented.