The role of spin-flip assisted or orbital mixing tunneling on transport through strongly correlated multilevel quantum dot

•Thermopower coefficient and conductance in the SU(N) Kondo regime exhibit quantization steps.•Giant thermopower effect is predicted for strong channel mixing.•For even N and full orbital mixing (N/2) level SU(N/2) Kondo effect is forseen. Using the slave boson Kotliar-Ruckenstein approach (SBMFA) for N level Anderson model, we compare fully symmetric SU(N) Kondo resonances occurring for spin and orbital conserving tunneling with many-body resonances for the dot with broken symmetry caused by spin, orbital or full spin-orbital mixing. As a result of interorbital or spin flip processes new interference paths emerge, which manifests in the occurrence of antibonding Dicke like and bonding Kondo like resonances. The analytical expressions for linear conductances and linear temperature thermopower coefficient for arbitrary N are found.