Hint of a new scalar interaction in LHCb data?

We explain recent LHCb measurements of the lepton universality ratios, R_D(*)τ /≡ B(B̄ → D(*)+ τ ⁻ ν ̄_τ )B(B̄ → D(*)+ ⁻ ν ̄_ ) R D ( ∗ ) τ / ℓ ≡ B ( B ¯ → D ( ∗ ) + τ - ν ¯ τ ) B ( B ¯ → D ( ∗ ) + ℓ - ν ¯ ℓ ) and R(Λ c⁺)τ / ≡ B(Λ b → Λ c⁺ τ ⁻ ν ̄τ)B(Λ b → Λ c⁺ ⁻ ν ̄) R ( Λ c + ) τ / ℓ ≡ B ( Λ b → Λ c + τ - ν ¯ τ ) B ( Λ b → Λ c + ℓ - ν ¯ ℓ ) with =μ ℓ = μ , via new physics that affects RDτ / R D τ / ℓ and R(Λ c⁺)τ / R ( Λ c + ) τ / ℓ but not RD^*τ / R D ∗ τ / ℓ . The scalar operator in the effective theory for new physics is indicated. We find that the forward-backward asymmetry and τ τ polarization in B̄ → D⁺ τ ⁻ ν ̄τ B ¯ → D + τ - ν ¯ τ and Λ b → Λ c⁺ τ ⁻ ν ̄τ Λ b → Λ c + τ - ν ¯ τ decays are significantly affected by the scalar interaction. We construct a simple two Higgs doublet model as a realization of our scenario and consider lepton universality in semileptonic charm and top decays, radiative B decay, B -mixing, and Z → b b̄ Z → b b ¯ .