Static Quantities of the W-Boson in the MSSM

Abstract

We systematically analyze the anomalous dipole $\Delta k_{\gamma}$ and quadrupole $\Delta Q_{\gamma}$ moments of the W gauge bosons in the context of the minimal supersymmetric standard model as functions of the soft SUSY breaking parameters $A_0,m_0,M_{1/2}$ and the top quark mass. The severe constraints imposed by the radiative breaking mechanism of the electroweak symmetry\,$ SU(2)\times U(1)$\, are duly taken into account. The supesymmetric values of $\Delta k_{\gamma}$ and $\Delta Q_{\gamma}$ can be largely different, in some cases, from the standard model predictions but of the same order of magnitude for values of \quad $A_0,m_0,M_{1/2} \leq {\cal O}(1 TeV) $. Therefore possible supersymmetric structure can be probed provided the accuracy of measurements for $\Delta k_{\gamma}$, $\Delta Q_{\gamma}$ reaches $10^{-2}-10^{-3}$ and hence hard to be detected at LEP2. If deviations from the standard model predictions are observed at LEP2, most likely these are not due to an underlying supersymmetric structure. In cases where $M_{1/2} \ll A_0,m_0 $, the charginos and neutralinos may give substantial contributions saturating the LEP2 sensitivity limits. This occurs when their masses $m_{\tilde C},m_{\tilde Z}$ turn out to be both light satisfying $m_{\tilde C}+m_{\tilde Z} \simeq M_W $. However these extreme cases are perturbatively untrustworthy and besides unnatural for they occupy a small region in the parameter space. }