[Clascomment] OPT-IN: Measurement of Single and Double Spin Asymmetries in Deep Inelastic Pion Electroproduction with Longitudinally Polarized Target

[Reinhard Schumacher]

Dear Harut et al.,

	I have read your draft paper “Measurement of Single and Double Spin Asymmetries in Deep....Target”.  It strikes me as a valiant attempt to make the most of some leading-edge experimental results from CLAS, but using models that do not make clear incisive predictions.  The writing is good, but there are a few places where you can make the case a little stronger for the non-expert reader, I think.

Page 1, column 2, line 5:  you have a dense 10-line sentence here with bad punctuation that I recommend you split up into several sentences.  For example, describe the physical meaning of the h and H functions in a separate sentence.  

Page 1 column 2,  paragraph 2, line 6: use “...been performed using lattice methods.”  

Page 2, col 1, para 1, line -2 from the bottom: use “...from THE rho (from 5PERCENT to 20% for...”

Page 2, col 1, -4 lines from bottom: I would replace the word ‘errors’ with ‘uncertainties’

Page 2, col 2, para 4:  Figure 2 is one of your two main results, and you make a true statement that the distributions are consistent with being “flat”.  The physics interpretation you give seems to hinge on the distributions being non-flat, or at least different for the different pion flavors.  The statistical evidence is weak, unfortunately.  You then go on to quote the “Torino” calculation of A1 in terms of kinematic variables,  and distributions, and ratios thereof.  The reader is left without a clear idea of what you think this all means.  You need a summary statement of this part of the paper.  Can you add something like: “The curves shown are the same for all three pions, apart from the overall scale.  The slight discrepancy between these flavor-independent shapes and the measured distributions indicates a possible flavor-dependence of the functions g1 and f1.  If confirmed, this would indicate...”

Page 3, col 1, near bottom:  It is not clear to me why comparing the two functions gives a measure of whether the CLAS phi dependence is affecting the results or not.  It will probably be less clear to an outside reader.  Can you improve this sentence?

Good luck with the submission process!

Reinhard.