Scalar top quark as the next-to-lightest supersymmetric particle

Abstract

We study phenomenologically the scenario in which the scalar top quark is lighter than any other standard supersymmetric partner and also lighter than the top quark, so that it decays to the gravitino via $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{t}\ensuremath{\rightarrow}{W}^{+}b\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{G}.$ In this case, scalar top quark events would seem to be very difficult to separate from top quark pair production. However, we show that, even at a hadron collider, it is possible to distinguish these two reactions. We show also that the longitudinal polarization of the final ${W}^{+}$ gives insight into the scalar top quark and W-ino--Higgsino mixing parameters.