Confronting electroweak fine-tuning with No-Scale Supergravity

Applying No-Scale Supergravity boundary conditions at a heavy unification scale to the Flipped SU(5)SU(5) grand unified theory with extra TeV-scale vector-like multiplets, i.e.   No-Scale F-SU(5)F-SU(5), we express the Z  -boson mass MZMZ as an explicit function of the boundary gaugino mass M1/2M1/2, MZ2=MZ2(M1/22), with implicit dependence upon a dimensionless ratio c of the supersymmetric Higgs mixing parameter μ   and M1/2M1/2. Setting the top Yukawa coupling consistent with mt=174.3 GeVmt=174.3 GeV at MZ=91.2 GeVMZ=91.2 GeV, the value of c   naturally tends toward c≃1c≃1, which indirectly suggests underlying action of the Giudice–Masiero mechanism. Proportional dependence of all model scales upon the unified gaugino mass M1/2M1/2 in the No-Scale F-SU(5)F-SU(5) model suggests one possible mechanism of confronting the electroweak fine-tuning problem.