[Clascomment] OPT-IN: Transverse Polarization of Sigma+(1189) in Photoproduction on a Hydrogen Target

[Daniel Carman]

					December 21, 2012


Dear Chandra and Moskov,

I have read through your paper on the Sigma+ polarization. This paper is in serious need
of grammar improvements. There are just way too many for me to type them up. I will 
therefore give my marked up copy to one of you when you are next at JLab. However, I
did want to include my other comments here so that other reviewers can see what I found
if they are so interested. If have any questions, let me know.

My comments are referenced to the paper version dated Dec. 18, 2012 that was
provided for the CLAS review.


			   Regards,

				  Daniel

********************************************************************
General: This paper is plagued by a problem with the tense. Most often you should be using
         the past tense. Please see my marked up version of the text for corrections.

Page 1.
 Left column.
   First paragraph.
     - Line 10. Your choice of references [3-7] is not fully appropriate. I do not find Ref.[3]
                appropriate for a data reference (it is a "higher-level" analysis work) and
                your Ref.[4] is just not appropriate. You should reference the relevant CLAS
                publications from McNabb and McCracken for K+Lambda and reference Dey for
                K+Sigma0.
   Second paragraph.
     - This discussion is all based on the simple non-relativistic quark model. Yet the discussion
       here does not explicitly mention this underlying (and critical) assumption and presents a
       discussion as if it were based on a complete model..

 Right column.
   First paragraph.
     - Line 4. The sentence beginning "Polarization of Sigma+(1189) ..." should begin a new
               paragraph.
   Second paragraph.
     - You should also explicitly give the W range at this point as well as the photon energy range.

Page 3.
 - Fig. 4. I cannot distinguish any of your line types in this figure.

Page 4.
 - Eq.(7), the angular distribution formula, is listed as based on Refs.[17-21]. After reading through
   these papers, I would urge you not to include Refs.[17-20]. They are not appropriate as references
   for Eq.(7). Also, your notation does not follow what is written in Ref.[21], the only paper that
   gives a form for Eq.(7). There the angle theta is the angle between the hyperon and the meson, not
   the hyperon and the baryon as you are assuming. My feeling is that you are using a non-standard
   convention and should change your convention to match Ref.[21].

Page 5.
 - Fig. 6. You should explicitly state that you are presenting bin averaged results (for all of your
   figures). Also, you should include units on your E_gamma ranges in each sub-figure and include 
   horizontal lines at +/- 1. I also strongly urge you to include W labels as well on each subplot.

Page 6.
 - Fig. 7. Your notation so far has been in terms of cos theta. Now you have suddenly switched to
   theta labels. I recommend that you remain consistent. Label your subplots with cos theta ranges.
   Also I strongly suggest that you add a W axis to these plots and add horizontal lines at +/- 1.

Page 7.
 - Fig. 8. I am not sure what you are showing in these plots. Better said, I am not sure how you
   have displayed the results shown. Have you averaged the JLab and SAPHIR data sets to be able
   to plot them for the photon energy ranges shown. I think you should add a sentence saying what
   you did here. Also, why these two photon energy ranges? It seems arbitrary. I recommend that you
   give the W ranges as well.

Page 8.
 - Fig. 9. Why have you changed notation again? So far everything is listed in terms of photon energy.
   Now you change over to sqrt(s). Be consistent. Also, I think that you have kind of misled the
   reader with your discussion of the comparison. To me, I think that once you get beyond the resonance
   region, Regge phenomenology well describes both production processes. It is the same mechanism, and
   this is why the results agree. In the resonance region, the interference effects from different
   contributing s-channel states for the two different hyperons leads to different signatures in this
   observable. I do not think it is appropriate to try to make a blanket statement comparing Sigma0
   and Sigma+ over such a broad kinematic range.

Page 9.
 - Tables II, III, and IV. I think you need to be a bit more careful in explaining your notation for
   these tables. Your +/- ranges on cos theta and E_gamma are not uncertainties in these quantities.
   They are simply bin ranges. You are not presenting bin centered results, but average results over
   the extent of the bin. Thus it is not fair to quote them at a central kinematic point.
   
References.
 - Put the references in the order cited in the text.