The Masses of the Neutral CP-even Higgs Bosons in the MSSM: Accurate Analysis at the Two-Loop Level

TL;DR

This paper delivers a comprehensive diagrammatic calculation of the leading two-loop QCD corrections to the neutral CP-even Higgs-boson masses in the MSSM, merging them with the full one-loop on-shell results and incorporating refinements for higher-order electroweak and QCD effects. It employs an on-shell renormalization framework for the Higgs and squark sectors, and uses Dimensional Reduction with FeynArts and TwoCalc to evaluate the relevant two-loop diagrams, ultimately predicting m_h and m_H across the MSSM parameter space. A key outcome is that two-loop corrections substantially lower the one-loop predictions for m_h, with the precise values depending sensitively on stop mixing, MA, and other SUSY parameters; the authors provide a public code (FeynHiggs) for accurate phenomenological use and compare their results to RG-based approaches, finding good agreement in some regimes but notable deviations when squark mixing is large. These results have important implications for LEP2/Tevatron/LHC searches and for interpreting future precision measurements of the Higgs sector in SUSY scenarios.

Abstract

We present detailed results of a diagrammatic calculation of the leading two-loop QCD corrections to the masses of the neutral CP-even Higgs bosons in the Minimal Supersymmetric Standard Model (MSSM). The two-loop corrections are incorporated into the full diagrammatic one-loop result and supplemented with refinement terms that take into account leading electroweak two-loop and higher-order QCD contributions. The dependence of the results for the Higgs-boson masses on the various MSSM parameters is analyzed in detail, with a particular focus on the part of the parameter space accessible at LEP2 and the upgraded Tevatron. For the mass of the lightest Higgs boson, m_h, a parameter scan has been performed, yielding an upper limit on m_h which depends only on tan(beta). The results for the Higgs-boson masses are compared with results obtained by renormalization group methods. Good agreement is found in the case of vanishing mixing in the scalar quark sector, while sizable deviations occur if squark mixing is taken into account.

Figures (25)

• Figure 1: Feynman diagrams for the contribution of squark and quark loops to the Higgs-boson self-energies at the two-loop level ($H = \phi_1, \phi_2, A$).
• Figure 2: Feynman diagrams for the contributions of squark and quark loops to the Higgs-boson tadpoles at the two-loop level ($H = \phi_1, \phi_2$).
• Figure 3: One-loop counterterm contributions to the Higgs boson self-energies at the two-loop level ($H = \phi_1, \phi_2, A$).
• Figure 4: One-loop counterterm contributions to the Higgs-boson tadpoles at the two-loop level ($H = \phi_1, \phi_2$).
• Figure 5: One-loop diagrams for the squark and quark mass counterterms and for the squark mixing-angle counterterm.