TOWARDS A MODEL-INDEPENDENT ANALYSIS OF RARE B-DECAYS

Motivated by the experimental accessibility of rare B decays in the on going and planned experiments, we propose to undertake a model-indepen dent analysis of the inclusive decay rates and distributions in the pr ocesses B --> X(s) gamma and B --> X(s)l(+)l(-) (B = B-+/- or B-0(d)). We show how measurements of the decay rates and distributions in thes e processes would allow us to extract the magnitude and sign of the do minant Wilson coefficients of the magnetic moment operator m(b) ($) ov er bar s(L) sigma(mu nu)b(R)F(mu nu) and the four-fermion operators (( $) over bar s(L) gamma(mu)b(L))(($) over bar l gamma(mu)l) and (($) ov er bar s(L) gamma(mu)B(L)) (($) over bar l gamma(mu)gamma(5)l). Non-st andard-model effects could thus manifest themselves at low energy in r are B decays through the Wilson coefficient having values distinctly d ifferent from their standard-model counterparts. We illustrate this po ssibility using the examples of the two-doublet Higgs models and the m inimal supersymmetric models. The dilepton invariant mass spectrum and the forward-backward asymmetry of l(+) in the centre-of-mass system o f the dilepton pair in the decay B --> X(s) l(+)l(-) are also worked o ut for the standard model and some representative solutions for the ot her two models.