Searching for theCP-odd higgs boson of the minimal supersymmetric model at hadron supercolliders

The $\mathrm{CP}$-odd Higgs boson $A^0$ of a nonminimal Higgs model possesses no tree-level couplings to vector-boson pairs. As a result, many of the techniques employed to search for the standard model Higgs boson at the Superconducting Super Collider (SSC) and CERN Large Hadron Collider (LHC) are not likely to be useful in searches for the $A^0$. This paper focuses on the phenomenology of $A^0$ production and decay in the minimal supersymmetric model. We evaluate a comprehensive set of branching ratios for $A^0$ (which includes all two-body tree-level and one-loop decays into nonsupersymmetric final states), including the effects of leading-log radiative corrections. The one-loop decay $A^0\to \mathrm{ZZ}$ leads to the "gold-plated" signature $\mathrm{ZZ}\to l^{+}{l}^{-}{l}^{+}{l}^{-}$ and provides an observable signature for $A^0$ production at the SSC and LHC only over a very narrow region of parameter space. More promising signatures for the $A^0$ are also discussed.