Flavour Changing Neutral Currents, Weak-Scale Scalars and Rare Top Decays

Abstract

We examine the decays $t\to c\gamma$ and $c{Z}^0$ in the Standard Model with an extra scalar doublet and no discrete symmetry preventing tree-level flavour changing neutral currents. The Yukawa couplings of the new scalars are assumed to be proportional to fermion masses, evading bounds on FCNC's from the light quark sector. These rare top decays may be visible at the SSC.

Comments: (some wording changed, and several references added) 13 pages, 2 figures included, uses harvmac.tex and epsf.tex, UCSD/PTH 93-01