Speaker
Description
The decay of B mesons can be described in the Heavy Quark Expansion as the decay of a free bottom quark plus corrections which are suppressed by powers of 1/m_b. The focus of the talk will be on the calculation of the NNLO corrections to semileptonic and nonleptonic decays of a free bottom quark including a non-vanishing charm quark mass. For the semileptonic decays we obtain an analytic result by solving differential equations and fixing boundary conditions in the limit of a heavy charm quark. Our analytic expression can be compared to previous known results obtained via expansions in the mass ratio m_c/m_b. In a second approach we calculate precise numerical expansions of all master integrals with the help of differential equations which can describe the whole parameter space from m_c/m_b=1 to m_c/m_b=0. I will also give an outlook on the ongoing nonleptonic calculation, where the same techniques as in the semileptonic case are used.
