The effective potential and additional large radius compactified space-time dimensions

The consequences of large radius extra space-time compactified dimensions o n the four-dimensional one-loop effective potential are investigated for a model which includes scaler self interactions and Yukawa coupling to fermio ns. The Kaluza-Klein tower of states associated with the extra compact dime nsions shifts the location of the effective potential minimum and modifies its curvature. The dependence of these effects on the radius of the extra d imension is illustrated for various choices of coupling constants and masse s. For large radii, the consequence of twisting the fermion boundary condit ion on the compactified dimensions is numerically found to produce but a ne gligible effect on the effective potential.