Determining $\tan\beta$ at the NLC with SUSY Higgs Bosons

We examine the prospects for determining $\tan\beta$ from heavy Higgs scalar production in the minimal supersymmetric standard model at a future $e^+e^-$ collider. Our analysis is independent of assumptions of parameter unification, and we consider general radiative corrections in the Higgs sector. Bounds are presented for $\sqrt{s} = 500$ GeV and 1 TeV, several Higgs masses, and a variety of integrated luminosities. For all cases considered, it is possible to distinguish low, moderate, and high $\tan\beta$. In addition, we find stringent constraints for $3\lesssim\tan\beta\lesssim 10$, and, for some scenarios, also interesting bounds on high $\tan\beta$ through $tbH^{\pm}$ production. Such measurements may provide strong tests of the Yukawa unifications in grand unified theories and make possible highly precise determinations of soft SUSY breaking mass parameters.