Exploring charmonia ηc(6S,7S) in the Λc+Λ̅c- invariant mass spectrum of B0 → KS0Λc+Λ̅c-
Abstract
We analyze the B0 → KS0 Λc+ Λ̅c- decay recently observed by the LHCb Collaboration. The Λc+Λ̅c- invariant-mass spectrum exhibits an accumulation near 4.63~GeV, which we investigate together with the accompanying Λc+ KS0 spectrum constrained by the known Ξc(2923) and Ξc(2939) states. Our amplitude model includes a nonresonant term, the two established Ξc contributions, and high-lying charmonium states in the Λc+Λ̅c- channel. Guided by screened Godfrey--Isgur and quark-pair-creation calculations, we test the 4.63~GeV enhancement with a fixed ηc(6S) amplitude at $(4629.00, 24.20)$~MeV, {which improves the description of the 4.63~GeV region}, and examine a fixed ηc(7S) contribution at $(4718.84, 22.84)$~MeV, which improves the higher-mass region of the spectrum. We also evaluate the ηc(nS) → Λc+ Λ̅c- baryonic decays via a hadron-loop mechanism and estimate the B0 → KS0 ηc(nS) production in naive factorization. Within the narrow width approximation, the fit yields a ℬ(B0→ KS0ηc(6S)) ℬ(ηc(6S)→Λc+Λ̅c-) of about 6.2 × 10−6, while the factorization and hadron-loop calculations give rates roughly one to three orders of magnitude lower than the above fitted ratio. These results highlight the need for more precise data and a full amplitude analysis to determine the line shapes and clarify the nature of the higher-mass contribution.
Versions
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BibTeX
@misc{liu2026exploring,
title = {{Exploring charmonia $η_c(6S,7S)$ in the $Λ_c^+\barΛ_c^-$ invariant mass spectrum of $B^0 \to K_S^0Λ_c^+\barΛ_c^-$}},
author = {Cheng-Xi Liu and Jun-Zhang Wang and Xiang Liu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2608.15524},
eprint = {2608.15524},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.15524},
note = {CC0},
}
RIS
TY - UNPB
TI - Exploring charmonia η_c(6S,7S) in the Λ_c^+Λ̅_c^- invariant mass spectrum of B^0 → K_S^0Λ_c^+Λ̅_c^-
AU - Cheng-Xi Liu
AU - Jun-Zhang Wang
AU - Xiang Liu
PY - 2026
DA - 2026/10/24
PB - arXiv
DO - 10.48550/arxiv.2608.15524
UR - https://arxiv.org/abs/2608.15524
AB - We analyze the B^0 → K_S^0 Λ_c^+ Λ̅_c^- decay recently observed by the LHCb Collaboration. The Λ_c^+Λ̅_c^- invariant-mass spectrum exhibits an accumulation near 4.63~GeV, which we investigate together with the accompanying Λ_c^+ K_S^0 spectrum constrained by the known Ξ_c(2923) and Ξ_c(2939) states. Our amplitude model includes a nonresonant term, the two established Ξ_c contributions, and high-lying charmonium states in the Λ_c^+Λ̅_c^- channel. Guided by screened Godfrey--Isgur and quark-pair-creation calculations, we test the 4.63~GeV enhancement with a fixed η_c(6S) amplitude at $(4629.00, 24.20)$~MeV, {which improves the description of the 4.63~GeV region}, and examine a fixed η_c(7S) contribution at $(4718.84, 22.84)$~MeV, which improves the higher-mass region of the spectrum. We also evaluate the η_c(nS) → Λ_c^+ Λ̅_c^- baryonic decays via a hadron-loop mechanism and estimate the B^0 → K_S^0 η_c(nS) production in naive factorization. Within the narrow width approximation, the fit yields a ℬ(B^0→ K_S^0η_c(6S)) ℬ(η_c(6S)→Λ_c^+Λ̅_c^-) of about 6.2 × 10^−6, while the factorization and hadron-loop calculations give rates roughly one to three orders of magnitude lower than the above fitted ratio. These results highlight the need for more precise data and a full amplitude analysis to determine the line shapes and clarify the nature of the higher-mass contribution.
ER -