B0 → K∗ℓ+ℓ−

This study investigates the rare decay B → K∗ℓ+ℓ−, a process sensitive to new physics. We compute the branching ratios for ℓ = µ, e, incorporating state-of-the-art form factors and uncertainties. Our predictions are compared with LHCb experimental 
results, revealing a notable discrepancy quantified through the Wilson coefficient C9.
Using 2018 ATLAS data, we extract the S-wave fraction of the Kπ system in the decay B0 → K∗(892)J/ψ(→ e+e−). This work underscores the complexity of this decay and  their potential for probing new physics, while highlighting the importance of considering the Kπ system’s intricate dynamics in future rare B-meson decay analyses.