The msbar Renormalized Bottom Mass of Order {cal O}(α_s G_F M_t²) and its Application to Gamma(Hto bbar{b})

The renormalized mass of the bottom quark is calculated at the two loop level to order ${\cal O}(\alpha_s G_F M_t^2)$ in the $\msbar$ renormalization scheme. Different strategies for the computation are outlined. The result is applied to the partial decay rate $\Gamma(H\rightarrow b\bar{b})$ of the Higgs boson into bottom quarks. Expressing the width in terms of the running mass instead of the bottom pole mass allows to treat the ${\cal O}(\alpha_s G_F M_t^2)$ radiative corrections on the same footing as is commonly used in pure QCD calculations. The numerical values for the corrections are given and the sizes of different contributions are compared.