Charged - Higgs on R D ( ∗ ) , τ polarization , and FBA

couplings are needed to explain the RD and RD∗ anomalies. We show that when the upper limit of BR(Bc → τ ν̄τ ) < 30% is included, RD can be significantly enhanced while RD∗ < 0.27. With the BR(Bc → τ ν̄τ ) constraint, we find that the τ -lepton polarizations can be still affected by the charged-Higgs effects, where the standard model (SM) predictions are obtained as: P τ D ≈ 0.324 and P τ D∗ ≈ −0.500, and they can be enhanced to be P τ D ≈ 0.5 and P τ D∗ ≈ −0.41 by the charged-Higgs. The integrated lepton froward-backward asymmetry (FBA) is also studied, where the SM result is Ā (∗),τ FB ≈ −0.359(0.064), and they can be enhanced (decreased) to be Ā D(∗),τ FB ≈ −0.33(0.02).