Transverse lepton polarization in B→K^(*)l⁺l^-

We study the transverse lepton polarization (P_T) in the exclusive processes of B→Kl⁺l^- and B→K^*l⁺l^-. We find that the polarization is zero for B→Kl⁺l^- but nonzero for B→K^*l⁺l^-. The average values of P_T(B→K^*l⁺l^-) are 8.4×10^-4 and 2.0×10^-2 for l=μ and l=τ, respectively. The polarization asymmetry is a T-odd observable, which connects with the non-Hermiticity of the effective Hamiltonian, arising mainly from the cc̅ intermediate states. We also include the other two orthogonal components, longitudinal and normal polarizations, in our discussions.