[Clascomment] OPT-IN:Measurement of the Differential and Total Cross Sections of gd -> K0 Lambda(p) Reaction within the resonance region

[Reinhard Schumacher]

Hello Nick and Ken,

I've read most of your draft paper on "Measurements of ...K^0 Lambda... Region" and have some comments.  First let me complain that this is a rather rough draft of a publication, and I wish you and the Ad Hoc committee had done a more complete job before sending it out for collaboration review.  It would also have helped to add line numbers, making it easier for people to make comments.

Overall, the writing is a little too loose:  some things are not well explained and sometimes unsupported claims are made.    I'm sure these things can be improved and this will be a good publication.

Abstract: be consistent throughout the paper in how you spell "Kaon-MAID".  Last sentence: these --> this

page 1 lower left: "has neutral charge" --> "is neutral"

page 1 lower left:  where do you get the idea that t-channel exchange is excluded for K0Lambda?  Is that not only true at exactly zero degrees?   That is the kinematic limit were the Dirac algebra for the t-channel Feynman diagram vanishes.   At finite angles it is not true.

Figure 1:  Why is this in the paper?   I don't think it adds anything toward convincing the reader of your physics results.  The same is true of Figure 2.  The references to the CLAS standard publications should be entirely sufficient.

page 2 beginning:  "which produced a neutral"  --> "so as to produce a neutral" .  You can also find other awkward constructions in this paragraph to smooth out.  In the last sentence, what do you mean by "reconstruct the original event"?

(I did not read the experimental description this time around)

page 8 bottom left and Fig 12:  I do not think it is kosher to lift a figure from another paper and put it in your own.   For one thing, there are copyright issues.  Also it is not quite ethical.   You call the two sets of curve different "models", but in fact one can say it is the same "model" (same authors, same approach) with modified parameters.   I think you need to be more explicit about the contents of these two alternative curves, otherwise the reader has no idea what he is looking at.   It seems that you need to remove this figure in any case, so perhaps the point is moot.

page 9 Fig 13:  There is not nearly enough discussion about what this figure represents.   The caption needs to explain fully what the reader is looking at.  The top label belongs on the y axis, not the upper horizontal.    The corresponding text on page 8 needs to be expanded to *explain* what is being shown.    More generally, why are you showing this figure BEFORE you present the CLAS results and discuss them?   I think this figure and the discussion about it belongs AFTER Fig. 15.

page 9 bottom left:  not sure what you mean by "event median Egamma".   How does the geometric mean play a role here?

page 9 last sentence:  This is an essentially content-free statement.   I recommend removing it:  it expresses only your wishful thinking.

page 10 Fig 14:  Why are you not putting the same theory curves on this plot as on Fig 15?  Without curves, this is a very boring plot.   Also, I recommend making the in-panel text boxes large enough to read (same size at least as main text font), and also remove the parentheses around the angle on "cos" (to avoid clutter).

page 11, Fig 15:  Again, remove extraneous parentheses around angles to declutter the text.

One of the most notable qualitative observations here is that the cross section near threshold is large for BoGa and zero for KaonMAID.   The reader asks:  Why is that?  Can you provide a qualitative answer?   One would think that phase space should make the threshold cross section very small.   Is it that the S11 is so overwhelming in the BoGa calculation that it overpowers the small phase space?

page 12 top left:  The sentence "Although more difficult..." is vacuous and can be removed.

page 12 after bullets:  this sentence is grammatically challenged.  Try "These (remove 'specific') functions can fit the data and BE assumed to SPAN a variation OF realistic behaviors...."

page 12 last paragraph:  "analyses OF \gamma..."  ;  missing figure reference.   Starting with the sentence "This suggests that this effect...",   the discussion is highly speculative.   You don't really have evidence that the difference between channels is due to "missing interference terms".   Furthermore, there is a theorem, is there not, that in a total cross section all interference terms integrate to zero?   You only see interference effects in the angular differential cross section, I thought.   They vanish in the total cross section.

page 12 Fig. 17:   make the label panel big enough to read

page 13 last paragraph:  the way you phrase this paragraph implies that there is a discrete set of PWA "models" and we only need more data to find which "solution best fits the data."   That is not the message to send.   Clearly, with each new measurement the parameters in the BoGa PWA will be adjusted in a continuous way to best match the data.   There is no set of "alternative solutions" among which to pick.   That is an illusion propagated by some of the theory groups, and I don't think you want to mimic that artifice.   

page 13 Fig 18:  Nice looking results!

References:   I recently learned that Phys Rev C will let you publish papers with full article titles included in the list of references.    I recommend that you add the titles to the references.   This is a matter of tweaking the commands with which BibTeX is invoked.

That's all for this round,

Cheers,
Reinhard