[Clascomment] OPT-IN:Suppression of neutral pion production in deep-inelastic scattering off nuclei with the CLAS detector

[Reinhard Schumacher]

Dear Taisiya et al.,

Here are my comments on the "Suppression of neutral pions porduction.... CLAS detector" paper that is out for CLAS Collaboration review.

First of all, congratulations on getting this measurement made.   It is a long time in development, and you and the others have succeeded in producing a well-presented and significant result.

I have just a few comments and questions.

I find the first paragraph repellant, as in, I would not want to read this paper.   Statements about
creating new "gravitational mass from pure energy" ring as very naive and trusting of theory that is not very well understood (by you). I suggest removing this whole paragraph and starting the paper with a more modest and honest set of statements about how this worthy effort fits into the larger scheme of things.   Nothing in the later paper and the experimental results links to the statements made in the first few sentences. Don't promise things you cannot deliver with this work.

Page 2, Col 1, Paragraph 1, -4 lines from the bottom:  remove "nontrivial"

P2, C2, P4, L4: Use "...and reduce NUCLEON resonance region..."

P2, C2, P4, L7: You have a habit, here and later in the paper, of writing in mixed tense.   Good writing typically calls for being consistent about tense, at least at the paragraph level.   Usually it works best to write in past tense when describing the experiment and the analysis procedures.   You can switch to present tense when you are presenting results that are immediately in front of the eyes of the reader.   In this case, use "These cuts ansl ensureD xB>0.1 so that we WERE probing valence..."

A few lines later:  the sentence "The event phase space..." is very long and hard to parse initially.   Maybe use "...ratios: (i) with a total... over Q^2, and (ii) 54 bins..."

Fig 1 caption:  It is unhelpful to cram the formula for the function into the caption:   is adds nothing the reader cares to know.   Remove "The total...peak function".   Also, you make the erroneous statement that you computed the number of pi0's "from the height of the Gaussian".   You obviously need both the height and the width in the way you approached it.

Related to how you fitted the pi0 peak, you should have used a normalized Gaussian in your fitting function, with just a single parameter specifying the number of counts under the curve.   Your method is less good, because you ignore the correlated uncertainties between the fitted height and the fitted width.   That is, you have to take two fitted numbers to compute the total number of particles.   But the "error" on that number cannot be computed with ordinary error propagation on account of the correlations.   A better method would be, as mentioned, to fit directly to a normalized Gaussian that takes care of that mistake easily.

P3, C1,P2, -3 lines from bottom:  Use "two photon invariant mass".   Then, in the next sentence, it is not clear what you mean by "After energy correction...":  you do not specify what this correction is about.

P3, C2, P1, L4:  remove "new"

P3, C2, P1, last line:  again you make the incorrect statement about using only the "height of the Gaussian"

Fig 3:   The inserted panel in the figure is unreadable.   The journal will probably ask you to convey this information in some other way.

P5, C1, P1, various:   don't write in mixed tense.  In various places, use "includeD... varieD...varieD...HAD"

P5, C2, P2, L5: Use "The data show increasing suppression OF R_h for..."

P5, C2, P2, last lines:  You say "However, our Q^2....HERMES".   OK, but the reader is left hanging here.   It is as though you need to say something about what this restricted range mean to the results you are presenting.   Maybe remove this sentence and come back later to the comparison of CLAS and HERMES.

P6, C1, P2, L13:  You say "...due to the lenth contraction of the propagating quark..." , which is nonsensical.   What are you really trying to say?

P6, C2, P1, L1:  Use "BUT ALSO, the multiplicity ratio..."   The trouble for the reader here is that you are trying to get across two opposite effects, so you need to phrase it very clearly to separate one from the other.

P6, C2, P1, L3:   Again confusing.   You say "Such behaviour is opposite to the published HERMES results, which suggests.... "   This has not been made clear enough yet.   Are you saying the neutral pion result (CLAS) is different from the charged pion result (HERMES), or something else?

P6, C2, P2, L9:  I would say "...a wealth of new OPPORTUNITIES will be available..." becasue "physics" is not qunatifiable in the sense of wealth, like gold, for instance.  

That is all for now, 
Cheers, 

Reinhard