Coulomb and charge-symmetry breaking effects in the $^3$He ground state within the dressed dibaryon model developed recently for $2N$ and $3N$ forces are examined in detail. Particular attention has been paid to the Coulomb displacement energy $\Delta E_C=E_B(^3{ \rm H})- E_B(^3{ \rm He})$ and rms charge radii of $^3$H and $^3$He. A new scalar $3N$ force between the third nucleon a$ dibaryon is found to be very important for a correct description of the Coulomb energy and rms charge radius in $^3$He. In view of the new results for $\Delta E_C$ obtained here, the role of the effects of charge symmetry breaking in the nuclear force is discussed.
Categories: nucl-th