We introduce a new kind of non-relativistic ${ \cal N}{ =}\,8$ supersymmetric mechanics, associated with worldline realizations of the supergroup $SU(2|2)$ treated as a deformation of flat ${ \cal N}{ =}\,8$, $d{ =}1$ supersymmetry. Various worldline $SU(2|2)$ superspaces are constructed as coset manifolds of this supergroup, and the corresponding superfield techniques are developed. For the off-shell $SU(2|2)$ multiplets $({ \bf 3,8,5})$, $({ \bf 4,8,4})$ and $({ \bf 5,8,3})$, we construct and analyze the most general superfield and component actions. Common features are mass oscillator-type terms proportional to the deformation parameter and a trigonometric realization of the superconformal group $OSp(4^*|4)$ in the conformal cases. For the simplest $({ \bf 5, 8, 3})$ model the quantization is performed.
Categories: hep-th math-ph math.MP