The hidden-charm pentaquark states P₂₂ (4312) ^+, P₂₂ (4380) ^+, P₂₂ (4440) ^+, and P₂₂ (4457) ^+, all with isospin I = 1/2, were discovered by the LHCb collaboration in the decay process Λb⁰ J/ψp K^-. Although their quantum numbers remain undetermined, these states have generated significant theoretical interest. We analyze their spectrum and decay patterns-including those of their spin partners-within the Born--Oppenheimer effective field theory (BOEFT), a framework grounded in QCD. At leading order in BOEFT, we identify these pentaquark states as bound states in BO potentials that exhibit at short-distance a repulsive octet behavior and a nonperturbative shift due to the adjoint baryons masses, while asymptotically approaching the ΣcD threshold. We further incorporate O (1/mQ) spin-dependent corrections to compute pentaquark multiplet spin splittings. Based on the spectrum, semi-inclusive decay widths to J/ψ and ηc, and the decay width ratios to ΛcD and ΛcD^*, we provide the first theoretical predictions for the adjoint baryon masses, which can be confirmed by future lattice QCD studies. Moreover, our analysis supports the quantum number assignments: J^P = (1/2) ^- for P₂₂ (4312) ^+, (3/2) ^- for P₂₂ (4380) ^+, (1/2) ^- for P₂₂ (4457) ^+, and (3/2) ^- for P₂₂ (4440) ^+. We also present results for the lowest bottom pentaquarks.
Brambilla et al. (Mon,) studied this question.
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