Universal amplitude ratios in the Ising model in three dimensions

Abstract

We use a high-precision Monte Carlo simulation to determine the universal specific-heat amplituderatio A + /A − in the three-dimensional Ising model via the impact angleϕ of complex temperature zeros. We also measure the correlation-length critical exponentν from finite-size scaling and the specific-heat exponentα through hyperscaling. Extrapolations to the thermodynamic limit yieldϕ = 59.2(1.0)°,A + /A − = 0.56(3),ν = 0.630 48(32) andα = 0.1086(10). These results are compatible with some previous estimates from a variety of sources andrule out recently conjectured exact values.