Decoupling of the Right-handed Neutrino Contribution to the Higgs Mass in Supersymmetric Models

Recently, it has been argued that in the supersymmetric extension of the seesaw-extended Standard Model, heavy right-handed neutrinos and sneutrinos may give corrections as large as a few GeV to the mass of the lightest neutral CP-even Higgs boson, even if the soft supersymmetry-breaking parameters are of order the electroweak scale. The presence of such large corrections would render precise Higgs masses incalculable from measurable low-energy parameters. We show that this is not the case: decoupling is preserved in an appropriate sense and right-handed (s)neutrinos, if they exist, have negligible impact on the physical Higgs masses.