[Clascomment] OPT-IN: Measurement of the Helicity Difference E in omega -> pi+ pi- pi0 Photoproduction

[Daniel Carman]

Zulkaida et al.,

I have read through the draft of your new FROST omega paper. Below are my 
comments from reading through the manuscript. I think that the paper is
clearly written and the presentation is well laid out. Let me know if you 
have any questions.


					        Regards,
						
						Daniel

************************************************************************************
General:
 - Why do you refer to the measured observable as a "helicity difference"
   instead of (what I think is more appropriate) a "helicity asymmetry"?
 - I disagree with your use of "which" in most cases in the paper and point
   my issues out in the detailed comments below.
 - I would prefer that you replace the word "error" or "errors" with
   "uncertainty" or "uncertainties" throughout the paper. An error is a
   mistake. An uncertainty does not carry this connotation.
 - You are not consistent in the paper with your usage of "Figure" or "Fig.".
   Please review.

Page 1:
 Left column.
  Paragraph 1.
   - Line 4. Use "... experiments that study ...".
   - Line 6. Use "... program that focuses ...".
   - Line 14. Use "... vector meson, which then ...".
   - Line 16. Use "... no charge and share ...".
  Paragraph 2.
   - Line 11. I suggest "... Ref. [6] found that in order to describe
            the data, a smooth transition was required between the ...".
 Right column.
  Paragraph 2.
   - Line 3. Use "... $N^*$ resonances, ...".
   - Line 4. Use "... branching ratios, have been ...".
   - Line 18. Use "... single-channel PWA, but the ...".

Page 2:
 Left column.
  Paragraph 2.
   - Line 7. Awkward sentence. I suggest "Finally, the experimental results
          and a discussion of the observed resonance contributions are
          presented in Sections VI and VII.".
  Paragraph 4.
   - Line 4. Use "... $\omega \to \pi^0 \gamma$ and $\omega \to \pi^+\pi^-\pi^0,
          and was presented in four energy bins that cover an energy ...".
 Right column.
  Paragraph 2.
   - Line 8. I suggest "... the full $\omega$ solid angle.".
  Paragraph 3.
   - Line 4. Use "... spin-density matrix elements ...".
  Paragraph 4.
   - Line 6. Use "pseudo-randomly".
   - Line 12. The sentence "The determination of the degree of circular
           polarization ... transfer [23]." is essentially repeated in
           full on the next page that presents Eq.(3). I do not think this
           sentence is therefore necessary and would suggest that it be
           dropped.
  Paragraph 5.
   - Line 3. Use "Hall B photon tagger".

Page 3:
 Left column.
  Paragraph 1.
   - Line 6. The sentence that begins "In this experiment, the tagging ..."
          should begin a new paragraph.
 Right column.
  Paragraph 1.
   - Line 3. Use "... event trigger that required ...".

Page 5:
 Right column.
  Paragraph 1.
   - Line 5. I prefer "... nonetheless generated ...".

Page 6:
 Fig. 6 caption.
  - Line 2. Use "... events that were subjected ...".
 Left column.
  Paragraph 2.
   - Line 2. Use "... coordinates that describe ...".
   - Line 10. Use "phase space".
 Right column.
   - Two lines after Eq.(8). Use "... density functions, ...".

Page 7:
 Left column.
   - Line after Eq.(10). Use "... where ... and ... indicate if the photon ...".
  Section VI.A.
   Paragraph 2.
    - Line 1. Use "In an effort to resolve these ...".
    - Line 4. Use "... Eqs. 10 and 11 ...".
    - Line 5. Use "... polarization and the target polarization ...".
 Right column.
  Paragraph 4.
   - Line 2. Use "... helicity states at a rate of ...".
   - Line 8. Use "... asymmetry was calculated from the ...".

Page 8:
 Fig. 7 caption.
  - Line 1. Use "... helicity difference $E$ in the ...".

Page 9:
 Fig. 8 caption.
  - Line 1. Use "... helicity difference $E$ in the ...".
 Left column.
  Paragraph 3.
   - Line 5. Use "... [18,19], and $F$, $P$, ...".
   - Line 6. Use "... database, which includes ...".
   - Line 7. Use "photo-induced".
 Right column.
  Paragraph 1.
   - Line 2. Use "... PWA [7] that, at the time, ...".
   - Line 7. Use "... 2500~MeV, as well as ...".

Page 10:
 Left column.
  Paragraph 1.
   - Line 2. Use "... threshold, $J^P = 3/2^+$ ...".
   - Line 8. Use "... around $W$ ...".
   - Line 20. Use "... around $W$ ...".
   - Line 23. Use "... $\omega$ PWA.".
   - Line 24. Use "... $7/2^+$, and ...".

References:
 - [1]. Use "The GlueX Experiment at JLab, in preparation.".
 - [21]. The CLAS NIM paper is not a CLAS Collaboration paper.