OPT-IN:Photoproduction of Πand Σ0 hyperons using linearly polarized photons

[Daniel Carman]

Dave et al.,

I have read through the draft of the g8b results dated February 3 and was quite
pleased to see the analysis of these results is ready for publication. For the 
most part I think the paper is well constructed and clearly written. I include 
my comments (physics, style, and grammar) below. Let me know if you have any questions.


					        Regards,
						
						Daniel

************************************************************************************
General:
 - Use units of c=1 throughout as you are not consistent in your notation.
 - Even though you define $\theta_K$ as the CM angle of the kaon, I am not a
   fan of your notation. I much prefer notation like $\theta_K^*$ or $\theta_K^{CM}$
   to ensure there is no confusion with lab angle and to be consistent with notation
   in all of our other CLAS papers.

Page 1:
 - Line 66. Use "... has been carried out ...".
 - Line 76. Use "... and the angular range ...".

Page 2:
 - Line 60. Use "... of roughly 1~T in the ...".
 - Line 77. The Start Counter is not made from scintillator "tiles". I recommend
   "consisting of scintillation counters surrounding ...".
 - Line 84. Use "... flight, were used to deduce ...".

Page 3:
 - Line 42. Use "$K^+\Sigma^0$".
 - Line 45. Use "In order to "clean up" the ...".
 - Section B. 
  - Did you not apply momentum corrections to these data? 
  - Did you account for TOF paddle inefficiencies or study them for this analysis? 
  - What about the standard Tagger corrections for sag, etc?
  - Did you study acceptance corrections or quantify your level of sensitivity to them?
  - What about bad Tagger elements that would affect your statistics vs. W?

Page 4:
 - Section E title. Use "Background Corrections"
 - Line 40. Use "... of a Voigtian ...".
 - Line 54. Use "Section".
 - Line 67. Use "cross section".

Page 5:
 - Line 28. Nuisance Parameters? I loved this terminology!
 - Line 35. Use "Subsection".
 - Line 60. Use "Section".
 - Line 89. Use "$\Sigma^0$".
 - Line 92. Use "$\Sigma^0$".
 - Line 97. Use "... the statistical uncertainties.".

Page 6:
 - Fig. 3 and 4 captions. Use "... coverage in $W$ vs. $\cos \theta_K$ ...".
 - Fig. 3 and 4. I do not understand what the solid points represent based on your explanation.
   Are these the bin averages of your bins in both dimensions? If they are bin average values,
   how were these determined?
 - Line 12. Use "$K^+\vec{\Lambda}$".
 - Line 13. Use "$K^+\vec{\Sigma}^0$".
 - Line 24. The wording is not clear for what the blue curves are. How about "... whilst the
   blue curves are the result of a re-fit solution of the Bonn-Gatchina partial wave analysis
   of data for all channels, ...".
 - Line 28 and line 30. Use "$\cos \theta_K$".
 - Line 48. Use "... over the whole ...".

Page 7:
 - For the B-G fits, what is the advertised range of validity in W for the 2014 solution?
 - What is not clearly discussed is the parameter changes with the Bonn-Gatchina model fit
   to all of the data including these but not including any new states. What can you say?
 - For all data figures the x-axis range is not appropriate. The plots should start at ~1.7 GeV
   to eliminate all this unused white area from 1.6 to 1.7 GeV.
 - For all data figures, you do not mention what your horizontal error bars are supposed to
   represent?
 - Fig. 5 caption. Add a period at the end of the last sentence.
 - Discussion question: It is not clear the strategy that was employed for adding other N*, D*
   states to the fits. Was this a "random" approach or were the added states based on expectations
   from quark model calculations or 1- and 2-star states in the PDG?
 - Data plots. I am not clear on how you handled the 2-body analysis vs. 3-body analysis. You stated
   (if I understood what you wrote in Section III) that you somehow included both in your results
   shown here. That does not make sense to me. There are double counting issues and issues with
   different systematics, etc. Please clarify what you actually did. Also you claim that the
   2-body and 3-body final state analyses gave consistent results. Why did you not include a plot
   to show this?

Page 11:
 - Line 3. What do you mean by "baseline fit"?
 - Line 5. What do you mean by "diluted"?
 - Line 29. What is "S.br"?

Page 12:
 - Appendix A. I am not sure that I followed this sketchy discussion of how the data were
   analyzed. Given all of your symbols, it was pretty much all Greek to me.
 - Line 45. Use "cross section".
 - Line 46. Use "center of mass".

Page 13:
 - Line 23. End the equation with a period.
 - Line 61. Use "Section".

Page 14:
 - I would like to see the different collaborations (CLAS, LEPS, GRAAL) actually listed with the papers.
   e.g. J.W.C. McNabb {\it et al.} {\it (CLAS Collaboration)}, Phys. ...