REVIEW
$\psi(3S)$ and $\eta_c(3S)$ production in the $B^+$ decay processes
High Energy Physics - Phenomenology · Submitted 16 Oct 2026 · 59 references
Pith's verdict: A solid but parameter-dependent explanation of the B+ -> K+ psi(4040) branching fraction, with a testable prediction for eta_c(3S).
T0 · AI review
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Referee report
The paper
The paper claims
Long-distance meson loops resolve the anomalously large branching fraction of B+ → K+ ψ(4040) and predict η_c(3S) production.
The reading
What carries the argument
The meson-loop mechanism: after the B+ weak decay produces a pair of charmed-strange and anti-charmed mesons (e.g., D_s^+ D̅^0), these mesons rescatter by exchanging a charmed meson to form the final-state ψ(3S) and K+. This hadron-level loop describes the long-distance non-perturbative QCD contribution. The coupling constants of ψ(3S) and η_c(3S) to charmed mesons are extracted from the open-charm decay widths computed in the 3P0 model. A monopole form factor F($q^{2}$,$m^{2}$) = ($m^{2}$-$Λ^{2}$)/($q^{2}$-$Λ^{2}$) with Λ = m + α Λ_QCD (Λ_QCD = 220 MeV) regularizes the loops; the cutoff parameter α is fitted to the single available experimental branching fraction of B+ → K+ ψ(3S).
Extended reading notes
Core claim
The authors find that the short-distance pQCD prediction for B+ → K+ ψ(3S) is (2.$4^{{+0.7}}$_{-0.5})×$10^{{-4}}$, far below the PDG average of (1.6±0.5)×$10^{{-3}}$. Including long-distance contributions from meson loops—where the B+ first decays weakly into a charmed-strange meson and an anti-charmed meson, which then rescatter via the exchange of a charmed meson to produce ψ(3S) and a kaon—and adjusting a single cutoff parameter α in the monopole form factor (expected to be of order unity), they reproduce the experimental value for α in the range 1.95–2.88. Using the same parameter range, they predict the branching fraction of B+ → K+ η_c(3S) to be (0.$81^{{+0.31}}$_{-0.29})×$10^{{-3}}$, which is larger than that of B+ → K+ η_c(2S) and similar in pattern to the vector sector. They note that the BaBar data on B+ → J/ψ ω K+ show an enhancement near 4.0 GeV in the J/ψ ω mass distribution that could be η_c(3S), and urge Belle II and LHCb to search for it.
Load-bearing premise
The model parameter α in the monopole form factor is determined by fitting the single experimental branching fraction of B+ → K+ ψ(3S), and this same α range is then used to predict the B+ → K+ η_c(3S) branching fraction without any independent constraint.
Editorial extensions
If this is right
- The predicted branching fraction of B+ → K+ η_c(3S) is (0.81^{+0.31}_{-0.29})×10^{-3}, providing a clear target for experimental searches at Belle II and LHCb in the B+ → J/ψ ω K+ channel.
- Long-distance meson-loop contributions are shown to be essential for reproducing the branching fraction of B+ → K+ ψ(3S), indicating that pure pQCD calculations are insufficient for higher-excited charmonium production in B decays.
- A similar meson-loop mechanism may be important for other B decays to excited charmonia, such as ψ(4S) or ψ(4415), and should be included in future theoretical analyses.
- If η_c(3S) is observed with a branching fraction consistent with the prediction, it would support the identification of ψ(4040) as the dominant ψ(3S) state and validate the long-distance approach employed here.
Reading between the lines
- Because the cutoff parameter α is determined solely from one data point, the uncertainty in the predicted η_c(3S) branching fraction may be underestimated; future experimental measurement will serve as a stringent test of the model.
- If η_c(3S) is not found or its branching fraction differs significantly from the prediction, the meson-loop model might require revision (e.g., inclusion of additional intermediate states or a different form factor), or the identification of ψ(4040) as the pure ψ(3S) could be questioned.
- The framework can be applied to decays of bottom baryons (e.g., Λ_b) to excited charmonia, where long-distance effects might also be significant and observable at LHCb.
Original abstract
In the present work, we investigate the production of psi(4040) in the B+ -> K+ psi(4040) process. Our estimations indicate that the unexpectedly large branching fraction could be well reproduced by taking both the short-range perturbative and long-range non-perturbative QCD contributions into account, where the long-range non-perturbative part plays an important role. Considering the structural similarity of eta_c(3S) and psi(3S), we apply the same model parameters to investigate the production of eta_c(3S) in the B+ decay process, and the branching fraction is predicted to be (0.81 +0.31 -0.29) x 10^-3. Based on the estimations in the present work and the relevant experimental measurements, we suggest that the experimentalists search for eta_c(3S) in the J/psi omega invariant mass distributions of B+ -> J/psi omega K+ process at Belle II and LHCb Collaborations.
The compiled record
The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
The abstract, sentence by sentence
In the present work, we investigate the production of psi(4040) in the B+ -> K+ psi(4040) process. Our estimations indicate that the unexpectedly large branching fraction could be well reproduced by taking both the short-range perturbative and long-range non-perturbative QCD contributions into account, where the long-range non-perturbative part plays an important role. Considering the structural similarity of eta_c(3S) and psi(3S), we apply the same model parameters to investigate the production of eta_c(3S) in the B+ decay process, and the branching fraction is predicted to be (0.81 +0.31 -0.29) x 10^-3. Based on the estimations in the present work and the relevant experimental measurements, we suggest that the experimentalists search for eta_c(3S) in the J/psi omega invariant mass distributions of B+ -> J/psi omega K+ process at Belle II and LHCb Collaborations.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | In the present work, we investigate the production of psi(4040) in the B+ -> K+ psi(4040) process. | contribution 1.00 | 0.82 | 0.05 | asserted 0.84 |
| s1 | Our estimations indicate that the unexpectedly large branching fraction could be well reproduced by taking both the short-range perturbative and long-range non-perturbative QCD contributions into account, where the long-range non-perturbative part plays an important role. | interpretation 0.50 | 0.88 | 0.36 | hedged possibility 1.00 |
| s2 | Considering the structural similarity of eta_c(3S) and psi(3S), we apply the same model parameters to investigate the production of eta_c(3S) in the B+ decay process, and the branching fraction is predicted to be (0.81 +0.31 -0.29) x 10^-3. | result 0.93 | 0.91 | 0.27 | asserted 0.91 |
| s3 | Based on the estimations in the present work and the relevant experimental measurements, we suggest that the experimentalists search for eta_c(3S) in the J/psi omega invariant mass distributions of B+ -> J/psi omega K+ process at Belle II and LHCb Collaborations. | future work 1.00 | 0.33 | 0.42 | hedged possibility 0.99 |
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Figures
Showing 5 of the paper's 6 figures. See all figures in the PDF ↗ Figures reproduced from arXiv:2610.23273 by the authors.
References
Discussion
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