Exploring Possible Triangle Singularities in the Ξ b − → K − J / ψ Λ Decay
Round 1
Reviewer 1 Report
Dear Editor,
in the manuscript the authors analyze the the triangle diagrams for the decay process Ξb-→K-J/ψΛ. They find a total of 18 triangle singularities which occur when all intermediate particles are on mass shell and which produce peaks in the spectrum. Triangle singularities could play an important role in various reactions measured in experiments, such as in the updated LHCb measurement. I believe that the results of the paper are interesting enough to warrant publication in MPDI-Symmetry.
I found the manuscript in parts difficult to read. Especially Sections 2 and 3 are hard to follow if the reader is not entirely familiar with the framework. Here the authors could improve the manuscript by adding some more explanatory remarks for the not-so-familiar reader. For instance, after reading the sentence "The P-wave interaction of J/ψΛ system for the positive parity case is independent of the loop integration, while, for the negative parity case, the P-wave is in the chi_c1 Λ system, which provides a loop momentum q to the loop integral and suppresses the singular behavior at the chi_c1 threshold" I immediately wondered why?
Nevertheless, I believe that the paper is suitable for publication.
Best regards
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors investigate the effect of possible triangle singularities on the J/ψΛ invariant mass distribution in the process Ξb- --> K-J/ψΛ which can manifest itself by peak structures that would allow important conclusions about the spectrum of the intermediate states in the triangle loop. The considered process is a promising channel for experimental studies because it involves the charged K- meson in the final state. The considered effects may become important in the experimental search for hidden-charm strange pentaquarks.
The investigation is well-described with clear results that are relevant for ongoing experimental studies. I recommend the acceptance of the article in its present form.
Author Response
We would like to thank the reviewer for the positive assessment of our work.
Best regards,
Chao-Wei Shen, Hao-Jie Jing, Feng-Kun Guo and Jia-Jun Wu
Reviewer 3 Report
The paper describes the role of triangular singularities in the decay of csi_b into K^- J/psi Lambda. It uses the same methodology that was already applied to many other processes, in particular to the process Lambda_b ---> J/psi K- p in Ref. [31]. One of the authors is also an author of that paper, in fact. The csi_b baryon (composed by dsb valence quarks) is slightly heavier than the Lambda_b baryon (composed by the udb valence quarks), and more difficult to produce in pp collisions than the second one. I would thus expect that an experiment like LHCb would have less precise results for csi_b than for Lambda_b. Notwithstanding this, I think that this analysis deserves publication because it is not yet been presented elsewhere and might in any case have some experimental utitlity, besides contributing to shed lights on hidden-charm pentaquark states with strangeness.
I have three comments that I would be happy that the authors would address in a slightly revised version of the manuscript:
1) why limiting the study to triangle diagrams ? In other words, I see that in the diagrams in Fig.1 the interactions between the particles B and C appear always as four-point vertices. Same applies to the loop integral in formula 1. One should not instead consider that in these vertices a boson is exchanged with momentum square (k2-q)^2, and then instead of having triangles, one should write down boxes ?
2) The "gamma" appearing in Fig. 2 are never introduced in the text. In particular, in the text, the authors report amplitudes M, but did not write the relation between them and the normalized decay widths. I think this should instead be written explicitly, for completeness.
3) Again for completeness, I think that the authors should extend Fig.3 to also report the spin-parity cases of 3/2^+ and 3/2^-. They discuss them a bit in the text, but it would be nice to see also the results of the explicit calculation in the plots.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
