OPT-IN: New Λp Cross Sections and its Implication for Neutron Star Equation of State

[Daniel Carman]

Dear Joseph, Ken et al.,

I have read through the draft of your paper on the Lambda-p cross sections. I am
pleased to see that this has culminated in a paper draft for review. The approach
you have analyzed is definitely interesting. I wish you good luck in your submission
to PRL. I found the paper in fairly good shape. The majority of my comments are in
the "clean up" category. Let me know if you have any questions.

Regards,
Daniel
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General:
 - You have often used the present verb tense in your writing when you should be using
   the past tense. I have captured the issues in my comments below.
 - You should use math mode for listing particles, i.e. use "$N$" for nucleon, "$K$" for
   kaon, etc. I have captured the issues in my comments below.
 - You should not begin a sentence using an abbreviation. The main place where this
   happens in your paper is where you use "Fig." when you should use "Figure" (e.g. line
   120 and line 224).
   
Page 1:
 - Title. What you have is a bit awkward. How about "New $\Lambda p$ Cross Sections
   and Their Implication for the Neutron Star Equation of State"?
 - Line 2. Use "... to determine its equation ...".
 - Line 7. Provide a reference to the LIGO-Virgo results.
 - Line 8. Use "However, the presence of hyperons in the core will soften the EOS, and
    a stiffening of the EOS at the ...".
 - Line 8. I do not know what you mean by "soften" or "stiffen". A clarifying statement
    is warranted.
 - Line 15. Use "... better data are needed for $\Lambda p$ ...".
 - Line 17. Use "Nucleon-nucleon ($N-N$) scattering ...".
 - Line 22. This should be formatted to read "... and 1970s [6,7]."
 - Line 25. Use "... statistics is from Ref. [4] with ...".
 - Line 26. There is a problem here. "spread over 12 data points"? Should it not read
   "spread over 12 momentum bins"? (or whatever the bins are).
 - Line 27. Use "$\Lambda - p$".
 - Line 28. Keep units with their values using "$c \tau \sim 7.8$~cm".
 - Line 30. Use "$\Lambda - N$".
 - Line 31. Use "$N-N$", "$K-N$", "$\pi-n$".
 - Line 32. Use "The present results in this work improve ...".
 - Line 39. Use "liquid-hydrogen".
 - Line 41. You do not need to include Ref. [9] here as provided this already in line 38.
 - Line 41. Use "The CLAS detector consisted of six ...".
 - Line 42. Use "... identical spectrometers (called "sectors")." (You use the term "sector"
   on pp. 2 without defining it.)
 - Line 42. Use "Each spectrometer had three ...".
 - Line 44. You have not mentioned the photon tagger (or used Ref. [10]). You should include
   a mention and point to Ref. [10].
 - Line 44. Use "Plastic scintillators surrounded the ...".
 - Line 45. Use "... DC, which allowed for ...".
 - Line 46. Use "The DC and TOF were used to identify ...".
 - Line 48. Use "... can be found in Ref. [11].".
 - Eq.(1). End with a period for proper punctuation.
 - Line 54. Use "... of CLAS, was not required ...".
 - Line 55. Use "... required as it was identified using ...".
 - Line 58. Use "... proton, $p'$, was detected directly ... the $\Lambda'$ was detected ...".
 - Line 60. Use "... and $\pi^-$ were directly detected ...".
 - Fig. 1 caption:
   - Line 2. Use "liquid-hydrogen".
   - Line 4. Use "... in the target at vertex (2), ...".
 - Line 65. Use "... fiducial region selection, and event ...".

Page 2:
 - Line 68. Use "The electron beam was bunched ...".
 - Line 69. Use "... apart, which produced the ...".
 - Line 70. Use "The selection criteria allowed for ...".
 - Line 80. Use "... as the data and included an additional ...".
 - Line 89. Use "The scattering $\Lambda'$ was identified ...".
 - Line 90. Use "... of its decay products, ...".
 - Line 91. Use "These four-momenta produced a mass ...".
 - Line 93. Use "The peak was fit to a ...".
 - Line 95. Use "The data were selected at ... analysis (see Fig. 2b).".
 - Eq.(2). End with a comma for proper punctuation.
 - Line 104. The mass of a K+ is 493.7 MeV not 511 MeV. It looks in Fig. 2b that your Gaussian
   peak is not at the correct position. Any comment?
 - Line 107. Use "... $K^+$ mass was fit to a Gaussian ...".
 - Line 108. Use "... selection was made at ...".
 - Line 118. Use "... final state that can be ...".
 - Line 119. Use "Kinematic calculations were used ...".
 - Line 120. Use "Figure 3 shows ...".
 - Line 121. Use "... on the $x$-axis ...".
 - Fig. 2 caption:
   - Line 2. Use "... (top) and the missing mass ...".
 - Line 126. Use "... events that must be ...".
 - Line 133. Use "... of these events were detected, ...".
 - Line 134. Use "... it was possible to ...".
 - Line 135. Use "... which is well known.".
 - Line 136. Use "... yielded consistent results ...".
 - Line 139. Use "... incident $\Lambda$ could now be ...".

Page 3:
 - Eq.(3). End with a comma for proper punctuation.
 - Line 152. Use "... technique was used to ...".
 - Line 153. Use "This was done by selecting ...".
 - Line 155. Use "... as that about the peak.".
 - Line 157. Use "... sidebands were treated as ...".
 - Line 158. Use "... subtraction provided a ...".
 - Line 159. Use "... and provided a better ...".
 - Line 161. Use "... background was removed ...".
 - Line 164. Use "... background was taken as ...".
 - Line 165. Use "... nominal fit, while the polynomial acted as ...".
 - Line 167. Use "... $\Lambda$ was fit to a ... The yield was then ...".
 - Line 170. Use "... done that models the ...".
 - Line 181. Use "Beam flux calculations were more ...".
 - Line 183. Use "... beam that enters the target ...".
 - Eq.(4). End with a comma for proper punctuation.
 - Line 189. Use "... of the $\Lambda$ beam in the target, ...".
 - Line 191. Use "... novel beam like this, the average ...".
 - Line 195. Use "... was made that generated ...".

Page 4:
 - Line 197. Use "The angular distribution was simulated ...".
 - Line 198. "existing cross sections of the primary vertex". This does not make sense. Please
   review.
 - Line 201. Use "... particles were generated with ...".
 - Line 203. Use "... they were propagated ...".
 - Eq.(5). End with a comma for proper punctuation.
 - Line 209. Use "... length was then averaged ...".
 - Eq.(6). End with a comma for proper punctuation. Also define theta.
 - Line 215. "physical restrained" ... Huh? I have no idea what you are trying to say here.
 - Line 220. Use "Cross sections were calculated ...".
 - Line 221. Use "... bin and integrated over the full angular range as:".
 - Eq.(7). End with a comma for proper punctuation.
 - Line 223. Use "... of the $\Lambda$ beam, and ...".
 - Line 224. Use "Figure 5 shows ..."
 - Line 229. Use "... statistical uncertainties only.".
 - Line 236. Use "... event generator, which resulted ...".
 - Line 238. Use "The uncertainty from the ...".
 - Line 239. Use "... in detail in Ref. [11], was estimated ...".
 - Line 241. Use "... $pp$ combined to give ...".
 - Fig. 5. The key in the UR corner should be positioned so that it does not overlay any of the
   data points as it does now.
 - Fig. 5 caption:
   - Line 5. Use "... chiral EFT model [4]."
 - Line 243. What do you mean "detector-related variations"? 
 - Line 254. You need to provide references to the Julich and Nijmegan potentials here.
 - Line 262. Use "Figure 3 shows ...".
 - Line 269. Use "... $\Lambda p$ cross sections in the momentum ...".
 - Line 273. Use "We also note that ... $p_\Lambda = 1.6~GeV/c ...".
 - Line 275. Use "... channel that affects the elastic ...".

Page 5:
 - Line 284. Use "... scattering cross sections in this ...".
 - Line 288. Use "... 1.4~GeV/c, as well as ...".

References:
 - General - For some references you give the page range and in others just the first page number.
   It is standard just to give the first page number.
 - Put the references in the order cited in the text.
 - Ref. [11] is not complete. You need to provide a URL to the note (otherwise this reference is not
   particularly useful to the reader).
 - Ref. [12] is not appropriate. U. Shrestha is not a spokesperson for the g12 run group. If you are
   trying to provide a general reference for the g12 run group, you should give a complete reference
   to an existing g12 paper or CLAS note (with a URL).