We analyze some features of the role that extra dimensions, of radius R in the ${\mathrm{TeV}}^{-1}$ range, can play in the soft breaking of supersymmetry and the spontaneous breaking of electroweak symmetry. We use a minimal model where the gauge and Higgs boson sector of the MSSM are living in the bulk of five dimensions and the chiral multiplets in a four-dimensional boundary. Supersymmetry is broken in the bulk by the Scherk-Schwarz mechanism and transmitted to the boundary by radiative corrections. The particle spectrum is completely predicted as a function of a unique R charge. The massless sector corresponds to the pure standard model and electroweak symmetry is radiatively broken with a light Higgs boson weighing $\lesssim 110\hspace{0.5em}\mathrm{GeV}.$ The $\mu$ problem is solved and Higgsinos, gauginos, and heavy Higgs bosons acquire masses $\sim 1/R.$ Chiral sfermions acquire radiative squared-masses $\sim {\alpha }_i{/R}^2.$ The effective potential is explicitly computed in the bulk of extra dimensions and some cosmological consequences can be immediately drawn from it. Gauge coupling running and unification are studied in the presence of Scherk-Schwarz supersymmetry breaking. The unification is similar to that in the supersymmetric theory.

• Received 14 January 1999

DOI:https://doi.org/10.1103/PhysRevD.60.095008