Phase Transition Temperatures at Next-to-Leading Order
  Broken gauge symmetries are typically restored at high temperature, and the leading-order result for the critical temperature $T_c$ was found many years ago by Weinberg and by Dolan and Jackiw. I find a simple expression for the next-to-leading order correction to $T_c$, which is order $e T_c$ where $e$ is the gauge coupling. The result is a simple consequence of recent work on summing ring diagrams at high temperature in gauge theories. The result is valid when the Higgs self-coupling $\lambda$ is the same order as $e^2$, and it does not address the case of strongly first-order phase transitions, which arise when $\lambda \ll e^2$. 
Peter Arnold