  Since the calculation of $BR(B^- \to \eta^{\prime} K^-)$ in the framework of
QCD improved factorization method, developed by Beneke et al., leads to
numerical values much below the experimental data, we include two different
contributions, in an alternative way. First, we find out that the spectator
hard-scattering mechanism increases the $BR$ value with almost 50%, but the
predictions depend on the combined singularities in the amplitude convolution.
Secondly, by adding SUSY contributions to the Wilson coefficients, we come to a
$BR$ depending on three parameters, whose values are constrained by the
experimental data.
