We examine the validity of the 1-loop approximation to the effective potential at finite temperatures and present a simple test for its reliability. As an application we study the standard electroweak potential, showing that for a Higgs mass above 70 GeV, and afirly independent of the top mass (with $m_{ t} > 90 GeV$, the 1-loop approximation is no longer valid for temperatures in the neighborhood of the critical temperature.
Categories: hep-ph