[Clascomment] OPT-IN:Measurement of Exclusive pi0 Electroproduction Structure Functions and their Relationship to Transversity GPDs

[Marco Mirazita]

Dear authors,
here are my comments
Best regards,
         Marco
-----------------------------

As a general comment, I think that the contribution of the various GPDs to the terms in eq (1) should be better explained. Where the chiral even GPDs enter? 
In the abstract, it is said that the longitudinal GPDs fail to account for sigma_T and sigma_TT, but eq. 2 and 3 contain only transverse GPDs. Or these equations are model-dependent?



page 1, row 46
average parton momentum -> average longitudinal parton momentum

page 1, rows 67-68
According to eq. 2 and 3, this sentence is not correct for the DVMP of pi0. Maybe you could say 
"... such as DVCS and DVMP of charged pions..."

page 2, row 3-4
"This letter focuses primarily on THE DVMP OF PI0 and on the role ..."

page 2, row 16
"... GPD F .." -> "... GPD function .."
 
page 3 row 17
OTHER systematic studies ....

page 3, row 20
remove "to"

page 3 row 31-33
The sigma_U is the moment of "1"

page 3 row 40
I wonder if the results of Ref. 16 could be added to the plots.

page 3, row 57
<\bar{E}> should be <\bar{E}_T>

page 3, row 82
It is not clear what parametrization of the cross section Ref 15 is using. See my general comment

page 3, row 88
dominent -> dominant

page 3, row 88 and 91
<\bar{H}_T> is never defined

page 3 row 98
sigma_TT is negative, so maybe a modulus in the inequality should be added

page 3, row 110
This doesn't seem true to me, in fact at least ref. 14 agrees well with your data (see page 3, row 85)

page 4, caption of Fig. 2
You should add the symbol when describing the data, or when printing in black and white the various cannot be identified. 
Also, I guess the systematic band refers to sigma_U

page 4, rows 2-4
Again, it is not clear how the longitudinal GPDs anter in sigma_T and sigma_TT

page 4 row 9
it becomes -> they become