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We present results of extensive finite-temperature quantum Monte Carlo simulations on a SU(2) symmetric S=1/2 quantum antiferromagnet with four-spin interaction A. W. Sandvik, Phys. Rev. Lett. 98, 227202 (2007)10.1103/PhysRevLett.98.227202. Our simulations, which are free of the sign problem and carried out on lattices containing in excess of 1.6 x 10(4) spins, indicate that the four-spin interaction destroys the Néel order at an unconventional z = 1 quantum critical point, producing a valence-bond solid paramagnet. Our results are consistent with the "deconfined quantum criticality" scenario.
Melko et al. (Tue,) studied this question.