| Sumario: | We study the implications for Λb→Λ∗cℓν¯ℓ and Λb→Λ∗cπ− [Λ∗c=Λc(2595) and Λc(2625)] decays that can be deduced from heavy quark spin symmetry (HQSS). Identifying the odd parity Λc(2595) and Λc(2625) resonances as HQSS partners, with total angular momentum–parity jPq=1− for the light degrees of freedom, we find that the ratios Γ(Λb→Λc(2595)π−)/Γ(Λb→Λc(2625)π−) and Γ(Λb→Λc(2595)ℓν¯ℓ)/Γ(Λb→Λc(2625)ℓν¯ℓ) agree, within errors, with the experimental values given in the Review of Particle Physics. We discuss how future, and more precise, measurements of the above branching fractions could be used to shed light into the inner HQSS structure of the narrow Λc(2595) odd-parity resonance. Namely, we show that such studies would constrain the existence of a sizable jPq=0− component in its wave-function, and/or of a two-pole pattern, in analogy to the case of the similar Λ(1405) resonance in the strange sector, as suggested by most of the approaches that describe the Λc(2595) as a hadron molecule. We also investigate the lepton flavor universality ratios R[Λ∗c]=B(Λb→Λ∗cτν¯τ)/B(Λb→Λ∗cμν¯μ), and discuss how R[Λc(2595)] may be affected by a new source of potentially large systematic errors if there are two Λc(2595) poles.
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