[Clascomment] OPT-IN: Double Polarisation Observable G for Single Pion Photoproduction from the Proton

[Daniel Carman]

Dear Nick et al.,

I have read through the draft of your paper on the G asymmetry in piN photoproduction
include my comments below. If you have any questions, let me know.

Regards,
Daniel
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Page 1:
 - Line 21. Use "$N\pi$".
 - Line 24. Use "... the SAID and Bonn-Gatchina approaches ...".
 - Line 26. Use "... have a large impact on the extracted properties ...".
 - Line 49. Use "... with a decisive impact ...".
 - Line 55. Use "... which predict many other "missing" resonances ...".
 - Line 57. Use "These studies have demonstrated ... photoproduction data to ...".
 - Line 58. It is fine to use "missing" resonances the first time you introduce this
      terminology, but you don't need to keep using the quotes around the word missing
      for subsequent use.
 - Line 62. Use "... spectrum of the nucleon.".
 - Line 63. Use "... studies of this spectrum arises ...".
 - Line 71. Use "... observables, information that is mandatory ...".

Page 2:
 - Line 92. Use "... their contributions will be ...".
 - Line 107. Use "cross sections".
 - Line 132. Use "... ($c.m.$) energy for the reaction ...".
 - Line 135. Use "... both states provides new ...".
 - Line 139. Use "Hall~B".
 - Line 149. Use "The tagger spectrometer upstream of CLAS allowed the ...".
 - Line 167. Use "Three incident electron beam energies ...".
 - Line 174. Use "... achieved was on the order of ...".
 - Line 179. Use "... impinged on the FRozen ...".
 - Line 179. You should mention the name of the CLAS dataset that was analyzed.
 
Page 3:
 - Line 185. Use "... in a strong magnetic field.".
 - Line 197. Use "... components (C, O, $^4$He, and $^3$He) ...".
 - Fig. 1 caption. Line 2. Use "... the photon direction and the $y$ axis ...".
 - Line 220. Use "... kinematic bin was performed ...".
 - Line 254. Do not capitalize "carbon".
 - Footnote 1. Line 2. Use "... from the free and the bound protons within ...". 
 - Footnote 2. Line 6. Use "... the extraction of the observables, ...". 

Page 4:
 - Fig. 2 caption. Lines 4,5: Do not capitalize "carbon" or "butanol".
 - Line 280. Use "$\pm 3\sigma$".
 - Footnote 3. Line 1. Do not capitalize "carbon".
 - Footnote 3. Line 3. Use "... indicating a contribution from ...".
 - Line 289. Use "... determination of the beam photon and target ...".
 - Line 290. Use "... which contribute a 6\% uncertainty.".
 - Line 297. Use "... analysis procedure, see the supplementary ...".
 - You are required to put these data into the CLAS physics database before submission
   of the paper. You should include the url for the database here so that the interested
   reader can get your data if they are interested.
 - Line 303. Use "... (left panels for ...".
 - Line 304. Use "... \pi^+n$). The curves represent the previous phenomenological
    solutions from SAID ...".
 - Line 310. Use "... is well within the statistical uncertainties (see left ...".
 - Line 315. Use "forward-going".
 - Line 323. Use "... predict the features in the angular ...".
 - Line 324. Use "... describe well their magnitude.".
 - Footnote 4. Line 2. Here you use "CB at ELSA". Everywhere else you have "CBELSA".

Page 5:
 - Fig. 3 caption.
   - Line 1. Use "A subset of the measured double ... G, from this work for
       the reactions ...".
   - Line 3. Use "The error bars represent the ...".
   - Line 4. Use "The previous data for ...".
   - Line 5. Use "... came from the NINA ... [25]. The blue solid ..."
 - Line 336. Use "... the rich features ...".
 - Line 337. Use "... the magnitude, in particular ...".
 - Line 342. Use "... either reaction exists."
 - Line 346. Use "... in Fig. 3 at 1490~MeV is interesting.".
 - Line 347. Use "... older MAID solutions all ...".
 - Line 369. Use "... Refs.~[11,12] ...".
 - Line 375. Use "... Collaborations, gave a much better ...".
 - Line 379. Use "... in Figs.~4 and 5.".
 - Line 380. Use "Contributions from high-spin states were investigated ...".
 - Line 390. Use "... it provides better consistency ...".
 - Line 393. Use "... in addition to the $\Delta(2400)9/2^-$).".
 - Line 396. Use "... some influence on the high-energy tail ...".
 - Line 397. Use "... however, both of the 9/2 states ...".
 - Line 400. Use "... $\Delta(2200)7/2^-$ in addition to the $\Delta(2400)9/2^-$.".
 = Line 401. Use "The $\chi^2$ for G for the reaction ...".
 - Line 402. Here you have units of GeV applied to chi2. You also switch to 4 significant
     figures here were in line 394 you only had 3 significant figures.

Page 6:
 - Fig. 4 and Fig. 5 caption:
   - Line 1. Here you use "center-of-momentum". Everywhere else you use "center-of-mass".
   - Line 2. Use "The experimental data from this work are shown by the red circles with ...".
   - Line 5. Use "... evident at higher $W$.".
 - Line 403. Here you have units of GeV applied to chi2. See my note about significant
    figures for line 402.
 - Line 405. Use "... from the $\Delta(2200)7/2^-$ are much stronger.".
 - Line 410. Use "... 2120$\pm$20~MeV, which is ...".
 - Line 411. Missing units on width.
 - Lines 414, 416, 417, 431. You are missing the units associated with A1/2 and A3/2.
 - Line 420. Use "... both the $N(2190)7/2^-$ ...".
 - Line 423. Use "... checking for chiral restoration ...".
 - Line 423. Use "In the case of chiral ...".
 - Line 427. Missing units on the pole position.
 - Line 430. Use "The $A_{1/2}$ helicity coupling at the pole was found ...".
 - Line 443. Need a reference for the Julich-Bonn analysis.
 - Line 446. Use "... of lower-spin states, resulting ...".
 - Line 447. Use "... in an improved fit ...".
 - Line 453. Use "spin-polarised".

Page 7:
 - Line 461. Use "... particularly for high-$L$ ...".
 - Line 462. Use "... where missing resonances ...".
 - Line 463. Use "The new data were fit in the ...".
 - Line 464. Use "... partial wave analyses, ...".
 - Line 465. Use "... tightly constrained amplitudes.".
 - Line 469. Use "... fine tune the lower-spin states.".

References:
 - Please include the Collaboration names where applicable in the references.
 - Your style is not consistent. Sometimes you abbreviated the journal names (my
   preference) and at other time you spell them out in full.
 - Do not include preprint numbers for published papers.
 - [3]. Spurious "083C01".
 - [4]. Spurious "Baryon 1980:217".
 - [8]. Spurious "cited By 40".
 - [15]. Spurious "cited By 158".
 - [28]. Give the URL for the CLAS-Note.