OPT-IN: Measurement of the near-threshold J/ψ photoproduction cross section with the CLAS12 experiment

[Igor Strakovsky]

Dear Leading authors,

Thank you very much for your nice paper.  Let me make some comments and suggestions for your consideration.  Most of them are for presenting and interpreting results.

1) I am glad to see that you found a way to use a BH for the absolute normalization following GlueX development. Please add a ref on the GlueX2019 paper.

2) Actually, Fig 5 compares CLAS total Xec with JPAC [32] calculations, which is not brand new. Instead, let me suggest comparing it with Ulf Meissner and co-workers' results [Meng-Lin Du, V. Baru, Feng-Kun Guo, Ch. Hanhart, U.-G. Meissner, A. Nefediev, & IIS, Eur PhysJ C 80,1053 (2020)], which takes into account threshold effects and recent Craig Roberts and co-workers' results using Pomeron exchange and loop diagram, covered a broad energy range [Lin Tang, Hui-Yu, Minghui Ding, & C.D. Roberts, arXiv:2510.08845 [hep-ph]].  Last is accepted for publication in PRD.  Both show just predictions, and there is no fit to the data as JPAC did.

3) Most of the previous analyses looked for bumps to see any effects of the LHCb pentaquarks in the GlueX J/Psi threshold data. In contrast, our analysis of the GlueX2023 shows the possibility of seeing the effect of the LHCb 5q via destructive interference between the s-channel resonance and the non-resonance background [IIS, W.J. Briscoe, E. Chudakov, I.Larin, L. Pentchev, A. Schmidt, & R.L. Workman, Phys Rev C 108, 015202 (2023)].  Let me suggest adding this ref.

4) As GlueX2019 [ IIS, D. Epifanov, and L. Pentchev, Phys. Rev. C 101, 042201 (2020)] and GlueX2023 [IIS, W.J. Briscoe, P. Gubler, J.R. Pybus, A. Schmidt, and A. Somov,[arXiv:2512.08701 [hep-ph]] show that the threshold J/Psi data allow us to determine J/Psi-N scattering length, which is small, 3 mfm. Using CLAS12 measurements from Table 5, I can determine SL for comparison with previous GlueX results.  It deserves mention in this paper.

If the Leader authors agree, I can contribute to this manuscript and determine the N-J/Psi SL, or we will publish our follow-up determination.

Cheers, Igor