Squark Contributions to Higgs Boson Masses in the Next--to--Minimal Supersymmetric Standard Model

Abstract

Within the context of an effective potential formalism we calculate the contribution to Higgs boson masses in the next--to--minimal supersymmetric standard model from squark loops. We then supplement a previously performed renormalisation group analysis of the Higgs sector of this model with these results in order to determine the shift in the bound on the lightest CP-even Higgs boson mass as a result of squark effects. The improved bound on the lightest neutral CP-even Higgs boson mass, including squark contributions, is $m_h\le 146(139,149)$ GeV for $m_t=90(140,190)$ GeV. For $m_t=190$ GeV squark effects contribute 23 GeV to the bound, with smaller contributions for small $m_t$ values.

Comments: 14 pages plus one postscript figure available separately; SHEP-92/93-18