• Accepted Paper

λ, ρ, and σ Regge trajectories for the quadruply heavy pentaquark bbu‾cc in the diquark-triquark picture

Xin-Ru Liu, Qi Liu, and Jiao-Kai Chen

Phys. Rev. D - Accepted 16 September, 2026

DOI: https://doi.org/10.1103/ng9j-c8gj

Abstract

Systematic investigations of four series of Regge trajectories for quadruply heavy pentaquarks are still lacking. Using the diquark and triquark Regge trajectory relations, we propose the Regge trajectory relations for the quadruply heavy pentaquark bbu‾cc: M=2mb+2mc+mu+5C/2+βxλ(xλ+c0xλ)2/3+βxρ1(xρ1+c0xρ1)2/3+βxρ2xρ2+c0xρ2+βxσ(xσ+c0xσ)2/3. Four series of Regge trajectories, namely the λ-, ρ1-, ρ2-, and σ-trajectories, are investigated. We demonstrate that accounting for the internal structure and substructure of pentaquarks is indispensable for constructing the ρ1-, ρ2-, and σ-trajectories; without such structural considerations, functional form and trajectory parameters can only be obtained via pure fitting against theoretical or experimental data. We further prove that the Regge trajectories of diquark 1, triquark, and diquark 2 (embedded within the triquark) do not correspond one-to-one to the ρ1-, ρ2-, and σ-trajectories. Nevertheless, these trajectories govern the behaviors of the respective ρ1-, ρ2-, and σ-trajectories. For both configurations (bb)(u‾(cc)) and (cc)(u‾(bb)), the λ-, ρ1-, and σ-trajectories exhibit behavior of M∼x2/3 (x=nr1,nr3,l1,l3,Nr,L), whereas the ρ2-trajectories exhibit behavior of M∼x (x=nr2,l2). The functional behavior of Regge trajectories for diquarks and triquark offers guidance for fitting the pentaquark Regge trajectories. Additionally, we provide rough estimates for spin-averaged masses of the λ-, ρ1-, ρ2-, and σ-excited states.

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