Higgs Boson Mass From Gauge-Higgs Unification

In certain five dimensional gauge theories the Standard Model Higgs doublet is identified, after compactification on the orbifold S^1/Z_2, with the zero mode of the fifth component of the gauge field. An effective potential for the Higgs field is generated via quantum corrections, triggered by the breaking of the underlying gauge symmetry through boundary conditions. The quartic Higgs coupling can be estimated at low energies by employing the boundary condition that it vanishes at the compactification scale \Lambda, as required by five dimensional gauge invariance. For \Lambda \gtrsim 10^{13}-10^{14} GeV, the Standard Model Higgs boson mass is found to be m_H = 125 \pm 4 GeV corresponding to a top quark pole mass M_t = 170.9 \pm 1.8 GeV. A more complete (gauge-Higgs-Yukawa) unification can be realized for \Lambda ~ 10^8 GeV, which happens to be the scale at which the SU(2) weak coupling and the top quark Yukawa coupling have the same value. For this case, m_H = 117\pm 4 GeV.