UPPER BOUND ON THE MASS SCALE OF SUPERPARTNERS IN MINIMAL N = 2 SUPERSYMMETRY

摘要

If N = 2 supersymmetry breaks to N = 1 supersymmetry at an intermediate scale m2 and then, later on, N = 1 supersymmetry breaks and produces standard model at a scale msusy such that m2>msusy, renormalization group evolution of three gauge couplings are altered above the scale m2, changing the unification scale and the unified coupling. We show that when we enforce this general condition m2>msusy on the solutions of the renormalization group equations, the condition is translated into an upper bound on the scale msusy. Using presently favored values of α1(mz), α2(mz), α3(mz), we get msusy < 4.5 ×109 GeV for the central value of α3(mZ). When low energy threshold effect is present, this bound gets smeared yet remains generally stable in the 109–1010 GeV range. We also show that if we demand string unification instead of having a unified gauge theory, this constraint can be changed by exotic hypercharge normalizations.