An upper bound for thet-quark mass from duality and unitarity

We attempt to predict the mass of thet-quark from the approach based on duality and unitarity, employing the values of known Regge slopes and vector meson masses. Thet-quark mass is shown to be bounded approximately by 65 GeV, using the maximum possible value for the γ slope. This upper bound is sensitive, however, to the γ slope, and hence it will be considerably reduced if the reliable value is obtained. The importance to find the χ _b state ((bb)³ P ₂) is emphasized. The χ _b mass is also predicted to be less than 9.89 GeV.