Scheme Independence of the Effective Hamiltonian for $b\to s\gamma$ and $b\to sg$ Decays

We present a calculation of the effective weak Hamiltonian which governs $b \rightarrow s, \gamma$and$b \rightarrow s , g$ transitions in two different renormalization schemes (NDR and HV). In the leading logarithmic approximation, we show that the coefficients of the effective Hamiltonian are scheme independent only when one takes correctly into account the scheme dependence of one- and two- loop diagrams. We demonstrate that in NDR there are contributions which were missed in previous calculations. These contributions are necessary to obtain scheme independent coefficients in the final results.