Inclusive B̄→ Xₛ ⁺⁻ at the LHC: theory predictions and new-physics reach

We present theoretical predictions for observables in inclusive B̄→ Xₛ ⁺⁻ suitable for measurements at hadron colliders through a sum-over-exclusive approach. At low q² we calculate the branching ratio and three angular observables. At high q² we provide the branching ratio and the ratio of the B → Xₛ ⁺⁻ rate with respect to the inclusive B → Xᵤ ν rate with the same phase-space cut. We compare our predictions to an extraction of the experimental rate through a sum-over-exclusive method using branching ratios of the exclusive B → K(*)μ⁺μ⁻ modes measured at LHCb. Our analysis does not support a recent claim about a deficit in the inclusive branching ratio in the high-q² region. Finally, we present current model-independent bounds on new physics and emphasize the potential of complementary analyses of B̄→ Xₛ ⁺⁻ at Belle II and the LHC.