It is shown that the scalar mesons $sigma$, $f_0(980)$ 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 $alpha$ showing up when only the pion cloud is taken into account. The electric polarizability of the proton $alpha_p$ confirms a two-photon width of the $sigma$ meson of $Gamma_{sigmagammagamma}=(2.58pm 0.26)$ keV.
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