The (B)over-bar → (K)over-barπll and (B)over-bars → (K)over-barKll distributions at low hadronic recoil

The rare multi-body decays (B) over bar -> (K) over bar pi ll and (B) over bar (s) -> (K) over bar Kll are both important as backgrounds to precision analyses in the benchmark modes (B) over bar -> (K) over bar *ll and (B) over bar (s) -> phi ll as well as sensitive probes of flavor physics in and beyond the standard model. We work out non-resonant contributions to (B) over bar -> (K) over bar pi ll and (B) over bar (s) -> (K) over bar Kll amplitudes, where l = e,mu, at low hadronic recoil in a model-independent way. Using the operator product expansion in 1/m(b), we present expressions for the full angular distribution. The latter allows to probe new combinations of vertical bar Delta B vertical bar = vertical bar Delta S vertical bar = 1 couplings and gives access to strong phases between non-resonant and resonant contributions. Exact endpoint relations between transversity amplitudes based on Lorentz invariance are obtained. Several phenomenological distributions including those from the angular projections to the S-, P-, D-waves are given. Standard model branching ratios for non-resonant (B) over bar -> (K) over bar pi ll and (B) over bar (s) -> (K) over bar Kll decays are found to be in the few 10(-8) region, but drop significantly if cuts around the K* or phi mass are employed. Nevertheless, the non-resonant contributions to (B) over bar (s) -> (K) over bar Kll provide the dominant background in the (B) over bar (s) -> (K) over bar *ll signal region with respect to the low mass scalars. In (B) over bar (s) -> (K) over bar Kll, the narrowness of the phi allows for more efficient background control. We briefly discuss lepton-flavor non-universal effects, also in view of the recent data on R-K.