Quantum fields, nonlocality and quantum group symmetries

We study the action of space-time symmetries on quantum fields in the presence of small departures from locality determined by dynamical gravity. It is shown that, under such relaxation of locality the symmetries of the theory cannot be described within the usual framework of Lie algebras but rather in terms of noncocommutative Hopf algebras or ``quantum groups.'' Similar ``quantizations'' of space-time symmetries are expected to emerge in the low-energy limit of certain quantum gravity models and have been used to describe the symmetries of various noncommutative space-times. Our result provides an intuitive characterization of the mechanism that could lead to the emergence of deformed coproducts in models of quantum relativistic symmetries.