2014/06/25 by Diganta Das, Das, Diganta, Gudrun Hiller +5
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph) #hep-ex #hep-ph
paper · pdf · doi:10.48550/arxiv.1406.6681
19+7 pages, 11 figures, 3 tables. v2: Clarifications and an explanatory figure (Fig 1) added; conclusions unchanged. Version accepted for publication in JHEP
arxiv created 2014/10/01 · arxiv updated 2014/10/02
The rare multi-body decays B->K pi ll and Bs->K K ll are both important as backgrounds to precision analyses in the benchmark modes B->K* ll and Bs->phi ll as well as sensitive probes of flavor physics in and beyond the standard model. We work out non-resonant contributions to B->K pi ll and Bs->K K ll amplitudes, where l=e,mu, at low hadronic recoil in a model-independent way. Using the operator product expansion in 1/mb, we present expressions for the full angular distribution. The latter allows to probe new combinations of |Delta B|=|Delta S|=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->K pi ll and Bs->K K ll 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->K pi ll provide the dominant background in the B->K* ll signal region with respect to the low mass scalars. In Bs->K K ll, 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 RK.