Comment on ‘High Precision Measurement of the Thermal Exponent for the three-dimensional XY Universality Class’

A recent paper [Burovski et al., cond-mat/0507352] reports on a new, high-accuracy simulation of the classical φ⁴ model (in the three-dimensional XY universality class). The authors claim that a careful scaling analysis of their data gives ν = 0.6711(1) for the thermal critical exponent. If correct, this would neatly resolve the discrepancy between numerical simulations and experiments on ⁴He. There is reason, however, to doubt the accuracy of the result. A re-analysis of the data yields a significantly higher value of ν, one that is consistent with other Monte Carlo studies.