Paper detail

Scalar mesons and polarizability of the nucleon

It is shown that the scalar mesons $σ$, $f_0(980)$ and $a_0(980)$ as $t$-channel exchanges quantitatively solve the problem of diamagnetism and give an explanation of the large missing part of the electric polarizability $α$ showing up when only the pion cloud is taken into account. The electric polarizability of the proton $α_p$ confirms a two-photon width of the $σ$ meson of $Γ_{σγγ}=(2.58\pm 0.26)$ keV.