Limits on the mass of the lightest Higgs in supersymmetric models

In supersymmetric models extended with a gauge singlet the mass of the lightest Higgs boson has contributions proportional to the adimensional coupling $\lambda$. In minimal scenarios, the requirement that this coupling remains perturbative up to the unification scale constrains $\lambda$ to be smaller than $\approx 0.7$. We study the maximum value of $\lambda$ consistent with a perturbative unification of the gauge couplings in models containing nonstandard fields at intermediate scales. These fields appear in scenarios with gauge mediation of supersymmetry breaking. We find that the presence of extra fields can raise the maximum value of $\lambda$ up to a 19%, increasing the limits on the mass of the lightest Higgs from 135 GeV to 155 GeV.