B s → K (*)ℓν̄, angular analysis, S-wave contributions and |V ub |

We analyse the B̄ₛ⁰→ K⁺l⁻ν̄ and B̄ₛ⁰→ K*+( → Kπ )⁻ν̄ decays that are valuable for extracting the CKM matrix element |V ub|. We calculate the differential and integrated partial widths in units of |V ub|2 based on various calculations of hadronic form factors and in particular the latest Lattice QCD calculation of the B s → K * form factors. For the decay B̄ₛ⁰→ Kπ ν̄ , we formulate the general angular distributions with the inclusion of the various partial-wave Kπ contributions. Using the results for the Kπ scalar form factor calculated from unitarized chiral perturbation theory, we explore the S-wave effects on angular distribution variables and demonstrate that they may not be negligible, considering the high precision expected in future measurements. We also briefly discuss the impact of the S-wave ππ contributions in the B⁻→ π⁺π⁻ v̄ decay and provide estimates for the mode B⁻→ K⁺K⁻ ν̄ . The studies of these channels in future can not only be used to determine |V ub|, but may also provide valuable information on the Kπ and ππ phase shifts.