[Clascomment] OPT-IN: Near Threshold Neutral Pion Electroproduction at High Momentum Transfers and Generalized Form Factors

[Reinhard Schumacher]

                                             11-7-12
Hello Puneet et al.,

Your draft paper on "Near threshold....Generalized Form Factors" makes
for nice reading.  It has a good balance between introductory
material, experimental details, and analysis results.  My comments are
mostly about a few points of wording and visual issues, plus a few
random typos.

Abstract line 4: use "near-HYPHEN-threshold"

After Eqs 2 and 3: Here is where you introduce the multipoles.  Later,
on lines 179 to 182, you finally get around to telling the reader what
the notation means.  I recommend that you insert these lines, with a
little modification, after line 82.  This will put the definition of
the variables right where they first are used.

Line 212, 214: use consistent past tense in the paragraph:
"surrounded", "generated", and "originated"

Figure 3: you don't comment on the blob at the bottom of the Monte
Carlo graph.  In the data graph is is clear that the electrons are
well separated from the MIPs, and that point is clear in the text, but
what is the extra stuff in the Monte Carlo simulation.

line 472: 'bremsstrahlung', spelling and no need to capitalize

line 512: the normalization discrepancy is a rather shockingly large
11%, and all you do is blame it on proton detection inefficiency.  Is
CLAS really worse at proton detection than pion detection?  I thought
we were better than 11% on the elastic cross section.  What is really
going on here?  I think the paper is a little weak in this point.

Figures 14, 15, 16: Putting the systematic error band on the data
points in a connect-the-dots fashion does not look very good to me.
It tend to clutter the view of the data in relation to the curves.  I
recommend that you do it the other way: put the grey band along the
bottom of the graph, or at zero.  The reader will have no trouble
interpreting that presentation.

After Eqs 32 to 35: you have defined all the other variables, so I
think for completeness, even though it is clear, you should add
mention of what P_l^\prime and P_{l+1}^{\prime\prime} are.

line 811 812: you indicate that the zero-crossing of G2 at >3, 2
and/or 4 GeV^2.  Those are not the numbers I would pick, looking at
your graph.  I would say >4, 2.2, and 3.5.

That is all for now,
Reinhard.