CP violation in the semileptonic B_l4 (B→Dπlν) decays: Multi-Higgs-doublet model and scalar-leptoquark models

CP violation from physics beyond the standard model is investigated in B_l4 decays: B→Dπlν̄_l. In the decay process, we include various excited states as intermediate states decaying to the final hadrons, D+π. We consider the semileptonic decay to a tau lepton family as well. CP violation is implemented through complex scalar-fermion couplings in the multi-Higgs-doublet model and scalar-leptoquark models beyond the standard model. With these complex couplings, we calculate the CP-odd rate asymmetry and the optimal asymmetry. We find that for B_τ4 decays the optimal asymmetry is sizable and can be detected at 1σ level with about 10⁶-10⁷B-meson pairs, for maximally allowed values of CP-odd parameters in those extended models.