Grand unification on noncommutative spacetime

We compute the beta-functions of the standard model formulated on a noncommutative spacetime. If we assume that the scale for spacetime noncommutativity is of the order of 2.2×10¹⁵ GeV, we find that the three gauge couplings of the standard model merge at a scale of 2.3×10¹⁷ GeV. The proton lifetime is thus much longer than in conventional unification models.