Anthropic Considerations in Multiple-Domain Theories and the Scale of Electroweak Symmetry Breaking

One of the puzzles of the standard model is why the mass parameter ${\mu }^2$, which determines the weak interaction scale, is closer to the quantum chromodynamics scale than to the grand unification or Planck scales. We consider a novel approach to this problem, based upon the idea that ${\mu }^2$ takes different values in different domains of the Universe. The whole range of values for ${\mu }^2$, from ${+M}_P^2$ to ${-M}_P^2$, is explored, and it is found that only for values in a narrow window is life likely to be possible. The observed value of ${\mu }^2$ is fairly typical of the values in this window.