Charge splitting in ${\pi}N\Delta$ formfactor

Abstract

Experimental data on $\pi N $ scattering in the elastic energy region $W \leq 1.45 GeV $ are analyzed within the $K$-matrix approach with effective Lagrangians. The charge splitting in $\delta^{++}_{33} $ and $\delta^{0}_{33}$ phases obtaned in the phase shift analisys is studed . It is shown that the change in the sign in the energy dependence of the phase difference can be obtained with different formfactors of the $\Delta^{++}$ and $\Delta^{0}$ only . This means that $\Delta^{++}$ and $\Delta^{0}$ has a different size in $\pi N $ interaction.The underlying nature of the observed phenomena is discussed.