Motivated by the indication of a new critical theory for the spin-1/2
Heisenberg model with a spatially staggered anisotropy on the square lattice as
suggested in \cite{Wenzel08}, we re-investigate the phase transition of this
model induced by dimerization using first principle Monte Carlo simulations. We
focus on studying the finite-size scaling of ρs12L and ρs22L,
where L stands for the spatial box size used in the simulations and
ρsi with i∈{1,2} is the spin-stiffness in the i-direction.
Remarkably, while we do observe a large correction to scaling for the
observable ρs12L as proposed in \cite{Fritz11}, the data for
ρs22L exhibit a good scaling behavior without any indication of a large
correction. As a consequence, we are able to obtain a numerical value for the
critical exponent ν which is consistent with the known O(3) result with
moderate computational effort. Specifically, the numerical value of ν we
determine by fitting the data points of ρs22L to their expected scaling
form is given by ν=0.7120(16), which agrees quantitatively with the most
accurate known Monte Carlo O(3) result ν=0.7112(5). Finally, while we can
also obtain a result of ν from the observable second Binder ratio Q2
which is consistent with ν=0.7112(5), the uncertainty of ν calculated
from Q2 is more than twice as large as that of ν determined from
ρs22L.Comment: 7 figures, 1 table; brief repor