Monte Carlo simulation calculation of the critical coupling constant for two-dimensional continuum ${\phi }^4$ theory

We perform a Monte Carlo simulation calculation of the critical coupling constant for the continuum two-dimensional $(\lambda /4){\phi }^4$ theory. The critical coupling constant we obtain is $[\lambda /{\mu }^2{]}_{\mathrm{crit}}{=10.26\mathrm{}}_{-.04}^{+.\mathrm{}08\mathrm{}}$.