hep-ph/9801425 THE EFFECTIVE WEAK MIXING ANGLE IN THE MSSM

The predictions of the MSSM are discussed in the light of recent LEP and SLD precision data. The full supersymmetric one loop corrections to the e ective weak mixing angle, experimentally determined in LEP and SLD experiments, are considered. It is demonstrated, both analytically and numerically, that, potentially dangerous, large logarithmic sparticle corrections are cancelled. The relative di erence factor k between the mixing angle de ned as a ratio of couplings and the experimentally obtained angle is discussed. It is found that k is dominated by the oblique corrections, while the non-oblique overall supersymmetric EW and SQCD corrections are negligible. The comparison of the MSSM with radiative electroweak symmetry breaking to the LEP+SLD precision data indicates that rather large values of the soft breaking parameter M1=2 in the region greater than 500 GeV are preferred. January 1998 E-mails : [email protected], [email protected], [email protected]