6533b85bfe1ef96bd12bbebc

RESEARCH PRODUCT

Scalar contributions to b→c(u)τν transitions

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Abstract We perform a comprehensive analysis of scalar contributions in b → c τ ν transitions including the latest measurements of R ( D ( ⁎ ) ) , the q 2 differential distributions in B → D ( ⁎ ) τ ν , the τ polarization asymmetry for B → D ⁎ τ ν , and the bound derived from the total width of the B c meson. We find that scalar contributions with the simultaneous presence of both left- and right-handed couplings to quarks can explain the available data, specifically R ( D ( ⁎ ) ) together with the measured differential distributions. However, the constraints from the total B c width present a slight tension with the current data on B → D ⁎ τ ν in this scenario, preferring smaller values for R ( D ⁎ ) . We discuss possibilities to disentangle scalar new physics from other new-physics scenarios like the presence of only a left-handed vector current, via additional observables in B → D ( ⁎ ) τ ν decays or additional decay modes like the baryonic Λ b → Λ c τ ν and the inclusive B → X c τ ν decays. We also analyze scalar contributions in b → u τ ν transitions, including the latest measurements of B → τ ν , providing predictions for Λ b → p τ ν and B → π τ ν decays. The potential complementarity between the b → u and b → c sectors is finally investigated once assumptions about the flavour structure of the underlying theory are made.