[Clascomment] OPT-IN: Resolving the proton form factor problem by comparing electron and positron scattering from the proton

[Reinhard Schumacher]

Hello TPE folks,

I'm glad you are about to send this important result off for
publication.  It looks like lots of people have pointed out the typos,
so I'll skip those.  I just have a few style and content comments for 
you to consider.

Abstract: The sentence "The cross section ratio increases with
descreasing epsilon..." is a little confusing on first reading because
we usually say what happens to a correlation with INcreasing value of
the independent variable.  Also, for the naive reader it might help to
say implicitly what the ratio was expected to be.  I suggest the
rewrite: "The cross section ratio increases ABOVE UNITY for smaller
values of epsilon at..."

(Page and line numbers for November 14 draft)
Page 2 line 38+: Here you discuss the TPECal to measure the "energy
distributions of the ... lepton beams".  This made me ask myself, OK,
what does that energy distribution look like?  You don't specify that
in the paper.  I suggest you put in a line stating "The teritary beams
had a momentum spread of XX% centered near YY GeV..." or something
like that.

Page 2 line 49: You are slipping into the jargon of the experiment
here.  It would be clearer if you say "... the CLAS torus magnet and
BEAM chicane magnet currents were ... reversed..."

General question that the paper does not address: despite listing a
large number of corrections and systematic studies, nowhere do you
mention positron annihilation.  How small an effect is that, and how
do you know it?

Page 3 line 38: Here again you mention the beam energy distributions,
but the paper does not indicate what that distribution is.  I think
you ought to have at least a sentence about that.

Page 3 line 43+: Here you mention discarding some data for reasons
that are not made clear in the paper.  I think this is a huge "red
flag" in the paper in the mind of a reader.  Other CLAS commentators
have pointed this out as well.  We discard data all the time when we
do experiments.  As long as we are confident we are doing it for
legitimate reasons, I don't think we need to burden the reader with
such details.  My recommendation is to remove mention of this in the
PRL paper.

Finally, I noticed Charles Hyde suggested a different title for the
paper since this work is not entirely definitive and it does not solve
all problems.  He has a point, I think, but if you change the title
you might consider saying "TOWARD resolving the proton..."

That's all.  Hope we beat the competition into print.

Reinhard