Electromagnetic Polarizabilities and Charge Radii of the Nucleons in the Diquark-model

Abstract

The diquark model is used to calculate the electromagnetic polarizabilities and charge radii of the nucleons for three different potentials. Making the scalar diquark lower in mass introduces a mixing angle $\theta $ between the $\left| 56\right\rangle $ and $\left| 70\right\rangle $ states ,which allows an improvement in value of all 6 properties. Generalizing the Gamov-Teller matrix and the magnetic moment operator to the diquark model gives constraints on this mixing. We obtain for the Richardson potential $\theta =23.2^{\circ },$ $\overline{\alpha }_p=7.9_{-0.9}^{+1.0}\times 10^{-4}fm^3,$ $\overline{\alpha }_n=7.7_{-0.6}^{+0.3}\times 10^{-4}fm^3,$ $\overline{\beta }_p=5.4_{-0.4}^{+1.6}\times 10^{-4}fm^3,$ $\overline{\beta }% _n=6.7_{-0.7}^{+1.3}\times 10^{-4}fm^3,$ $\left\langle r^2\right\rangle _p=0.37_{-0.03}^{+0.02}fm^2,$ $\left\langle r^2\right\rangle _n=-0.07_{-0.02}^{+0.03}fm^2.$ Additional pion cloud contributions could improve on all six results.