Parameter Bounds in the Supersymmetric Standard Model from Charge/Color Breaking Vacua

We calculate limits on the trilinear soft-breaking parameter, At, in the Minimal Supersymmetric Standard model by requiring the absence of nonzero top squark vacuum expectation values. Assuming a low tan�, which implies a large top Yukawa coupling, we also calculate one-loop corrections to the effective potential. The resulting numerical calculations of the charge/color breaking limits are presented as best-fit surfaces. We compare these results with the analytical limit, A 2 < 3(m 2 +m 2 ˜ q +m 2 ), and find that although this is a good estimate of the charge/color breaking bounds for a simplified model of the top sector, stricter bounds are found by a numerical minimization of the Minimal Supersymmetric Standard Model potential.