The evolution of standard model gauge couplings is studied in a nonsupersymmetric scenario in which the hierarchy problem is resolved by Higgs compositeness above the weak scale. It is argued that massiveness of the top quark combined with precision tests of the bottom quark imply that the right-handed top must also be composite. If, further, the standard model gauge symmetry is embedded into a simple subgroup of the unbroken composite-sector flavor symmetry, then precision coupling unification is shown to occur at $\sim {10}^{15}\mathrm{GeV}$, to a degree comparable to supersymmetric unification.

• Received 8 March 2005

DOI:https://doi.org/10.1103/PhysRevLett.95.171804