published [@Brax] for the case of non-universal soft terms in the framework of an orbifold compactification of the superstring, and these results are quite analogous to those presented here.

The most important consequences of the flavour independence of soft terms concern the $SU(2)\times U(1)$ symmetry breaking. It could be induced by a negative value of $m_{2}^{2}$, but for the potential to be bounded from below and to avoid colour or $e.m.$ symmetry breaking the universal parameter $m_0^2$ has to be positive, so that $m_{2}^{2}(\Lambda _{\mathrm{GUT}})>0$. For this reason, $m_{2}^{2}(v)<0$ has to be enforced by renormalization effects. This is a well-known feature of the MSSM as well, entailing a lower limit on the top Yukawa coupling. In the (M+1)SSM, the sign of $m_{2}^{2}$ could be made to flip by the coupling of the singlet fields even for a light top quark [@Desa]. The experimental value of top quark mass is perfectly consistent, however, with a negative $m_{2}^{2}$ at low energies from the effects of top-stop quantum loops.

Furthermore the cubic soft terms can also induce spontaneous symmetry breaking if the value of the parameter $A$ in (\[C\]) is large enough. Hence large values of $A_{\kappa }$ are preferred to give the 