Phenomenology ofVubfrom ratios of inclusiveBdecay rates

We explore the theoretical feasibility of extracting $V_{\mathrm{ub}}$ from two ratios built from B meson inclusive partial decays, $R_1=\Gamma \left(\overrightarrow{b}u\overline{c}{s}^{\prime }\right)/3\mathrm{}\Gamma \left(\overrightarrow{b}\mathrm{cl}\overline{\nu }\right)$ and $R_2=\left[\Gamma \right(\overrightarrow{b}cX\left)-\Gamma \right(\overrightarrow{b}\overline{c}X\left)\right]/\Gamma \left(\overrightarrow{b}cūd^{\prime }\right).\mathrm{}$ We discuss contributions to these quantities from perturbative and nonperturbative physics, and show that they can be computed with overall uncertainties at the level of 10%.