We define a class
of symplectic Lie groups associated with solvable symmetric spaces. We
give a universal strict deformation formula for every proper action of such a
group on a smooth manifold. We define a functional space where performing
an asymptotic expansion of the nonformal deformed product in powers of
the deformation parameter yields an associative formal star product on the
symplectic Lie group at hand. The cochains of the star product are explicitly
given (without recursion) in the two-dimensional case of the affine group
ax + b. The latter differs from the Giaquinto–Zhang construction, as shown by
analyzing the invariance groups. In a Hopf algebra context, the above formal star
product is shown to be a smash product and a compatible coproduct is
constructed.