$\tan\beta$ Determination From Heavy Higgs Boson Production at Linear Colliders

We study the production at future $e^+e^-$ linear colliders of the heavy neutral Higgs bosons $H$ and $A$ of the minimal supersymmetric standard model in association with top and bottom quarks. The cross sections have a strong dependence on the parameter $\tan\beta$, and thus provide a good way to determine it. At a linear collider with $\sqrt s = 0.5-1$ TeV and expected integrated luminosities, we find significant sensitivities for determining $\tan\beta$. In the Supergravity scenario, the sensitivity is particularly strong for $\tan\beta > 10$, reaching a 15% or better measurement. In the general MSSM scenario, the interplay between the $4b$ and $4t$ channels results in a good determination for $\tan\beta < 10$, while the sensitivity is weakened for higher values of $\tan\beta$.