Quadratic deformation of Minkowski space
  We present a deformation of the Minkowski space as embedded into the conformal space (in the formalism of twistors) based in the quantum versions of the corresponding kinematic groups. We compute explicitly the star product, whose Poisson bracket is quadratic. We show that the star product although defined on the polynomials can be extended differentiably. Finally we compute the Eucliden and Minkowskian real forms of the deformation. 
D. Cervantes, R. Fioresi, M. A. Lledo, F. A. Nadal
hep-th