  We study the quantum critical properties of antiferromagnetism in graphene at
T=0 within mean-field (MF) theory. The resulting exponents differ from the
conventional MF exponents, describing finite temperature transitions. Motivated
by this, we have developed the MF theory of general gapless phases with density
of states rho(E) |E|^r, r>-1, with the interaction as control parameter. For
r>2, the conventional MF exponents \'a la Landau are recovered, while for
-1<r<2, the exponents vary significantly with r. The critical interaction is
finite for r>0, therefore no weak-coupling solution exists in this range. This
generalizes the results on quantum criticality of the gapless Kondo systems to
bulk correlated phases.
