arXiv subjects
Publications and source records attributed to J. Haestier.
The precision observables M_W and g-2 of the muon are discussed in the framework of the MSSM. Recent progress in the evaluation of the theoretical predictions is described, and the MSSM predictions are compared with the SM predictions and the experimental values.
The dominant electroweak two-loop corrections to the precision observables M_W and s_w^eff are calculated in the MSSM. They are obtained by evaluating the two-loop Yukawa contributions of O(alpha_t^2), O(alpha_t alpha_b), O(alpha_b^2) to the quantity Delta rho. The result, involving the contributions from Standard Model fermions, sfermions, Higgs bosons and higgsinos, is derived in the gauge-less limit for arbitrary values of the lightest CP-even Higgs boson mass. A thorough discussion of the parameter relations enforced by supersymmetry is given, and two different renormalization schemes are applied. Compared to the previously known result for the quark-loop contribution we find a shift of up to +8 MeV in M_W and -4 * 10^-5 in s_w^eff. Detailed numerical estimates of the remaining uncertainties of M_W and s_w^eff from unknown higher-order contributions are obtained for different values of the supersymmetric mass scale.
The evaluation of the two-loop MSSM-contributions to the electroweak precision observables M_W and s_w^eff at order(alpha_t^2), order(alpha_t alpha_b), order(alpha_b^2) is presented. These contributions enter via Delta(rho), and it is explained in detail how one can retain the true, non-vanishing value of the MSSM Higgs boson mass M_h in spite of using the gauge-less limit in the calculation. The numerical results can be sizeable, in particular for strong squark mixing. By comparing the results in the on-shell and DR-bar renormalization schemes, the remaining theoretical uncertainty is found to be small.