First estimates of the $(\alpha +\beta {)}^{\pi }$ from two--photon experiments

Abstract

We carry out the semi--model analysis of existing data on the angular distributions of the $\gamma \gamma \to {\pi }^{+}{\pi }^{-},{\pi }^0{\pi }^0$ reactions with purpose to obtain S-wave cross section and D-wave's parameters. In the first time we obtain from experiment the sum of electrical and magnetic pion polarizabilities: $(\alpha +\beta {)}^{{\pi }^{+}}=0.28\pm 0.07$ (MARK-II \cite{M2}), \ \ $(\alpha +\beta {)}^{{\pi }^{+}}=0.38\pm 0.05$ (CELLO \cite{CELLO}), \ \ $(\alpha +\beta {)}^{{\pi }^0}=1.26\pm 0.06$ (Crystal Ball \cite{CB}) \ \ in units of $10^{-42}c{m}^3$ ($e^2=4\pi \alpha$).

Latex, 5 pages, no figures, ISU-IAP.Th94-01, Irkutsk