Properties of the π0, η, η′, σ, f0 (980) and a0 (980) mesons and their relevance for the polarizabilities of the nucleon

The signs and values of the two-photon couplings F-M gamma gamma of mesons (M) and their couplings g M N N to the nucleon as entering into the t-channel parts of the difference of the electromagnetic polarizabilities (alpha-beta) and the backward angle spin polarizabilities gamma(pi) are determined. The excellent agreement achieved with the experimental polarizabilities of the proton makes it possible to make reliable predictions for the neutron. The results obtained are alpha(n) = 13.4 +/- 1.0, beta(n) = 1.8 -/+ 1.0 (10(-4) fm(3)), and gamma((n))(pi) = 57.6 +/- 1.8 (10(-4) fm(4)). New empirical information on the'flavor wave functions of the f(0)(980)- and the a(0)(980)-meson is obtained.