Renormalizable

Renormalizability

Nonrenormalizable interactions in effective field theories rapidly become weaker as the energy scale becomes much smaller than the cutoff. The classic example is the Fermi theory of the weak nuclear force, a nonrenormalizable effective theory whose cutoff is comparable to the mass of the W particle. This fact may also provide a possible explanation for why almost all of the particle interactions we see are describable by renormalizable theories: others that may exist at the GUT or Planck scale simply become too weak to be observable. There is one exception: gravity, the exceedingly weak interaction of which is magnified by the presence of the enormous masses of stars and planets.