The trilinear neutral Higgs self-couplings in the MSSM. Complete one-loop analysis

The Higgs boson effective self-couplings $\lambda_{hhh}$ and $\lambda_{HHH}$ are calculated in the framework of the Minimal Supersymmetric Standard Model (MSSM) for the complete set of one-loop diagrams with one of the Higgs bosons off-shell. The comparison with previous results, where only the leading correction terms in the limiting case of large masses of virtual particles were calculated, is carried out. We analyse the dependence of the self-couplings on the energy and ${\tt tan} \beta$; it is demonstrated that the tree-level self-couplings could acquire substantial one-loop corrections, which could be phenomenologically important.