Quantum criticality in SU(3) and SU(4) antiferromagnets

We study the quantum phase transition out of the Néel state in SU(3) and SU(4) generalizations of the Heisenberg antiferromagnet with a sign-problem-free four-spin coupling (so-called JQ model), by extensive quantum Monte Carlo simulations. We present evidence that the SU(3) and SU(4) order parameters and the SU(3) and SU(4) stiffness go to zero continuously without any evidence of a first-order transition. However, we find considerable deviations from simple scaling laws for the stiffness even in the largest system sizes studied. We interpret these as arising from multiplicative scaling terms in these quantities that affect the leading behavior, i.e., they will persist in the thermodynamic limit, unlike the conventional additive corrections from irrelevant operators. We conjecture that these multiplicative terms arise from dangerously irrelevant operators whose contributions to the quantities of interest are nonanalytic.