[Clascomment] OPT-IN:Differential Cross Section for gamma d -> omega d using CLAS at Jefferson Lab

[Reinhard Schumacher]

Hello Ken and Taya,

I enjoyed reading you draft paper "Differential... gamma d --> omega d ... Lab" paper.  It seems to be a nice result.   I do have the following list of questions and suggestions for you to consider, however.

Abstract:   in line 3 you might want to say "...based on omega N rescattering..." because before that moment the reader doesn't know whether you mean rescattering with the deuteron on with one of the nucleons.

line 45:  It is not strictly true that the omega MUST decay to 3 pions: isospin is violated here, is it not?   The 2 pion branch is about 10%.  Somehow the statement in the paper here is incorrect.

line 95:  Is it really true that g10 had the tagger in the trigger?   I thought we found that the tagger is just about "always on", so including it in the trigger was not useful.

line 119:  I think you want  to use:  "...time that matcheD closeST with the..."

line 124:  hmmm....  claiming 3 significant digits?   I don't think that is plausible.  Give an uncertainty.

line 134:  here you point to a CLAS-note, which I suppose is OK.   But should you not also point to Taya's thesis on the CLAS thesis page?

line 149:  use "...missing mass OFF THE deuteron..."

line 150: "...equalED...  (pick a tense and stick to it)

Figure 2:  Something looks wrong to me here. In the upper panel (a) the vertical axis is the missing mass off d pi+ pi-, and events projected on to it are supposed to reveal the missing pi0.   But the projection of the red blob comes in at about 0.10 GeV/c^2, not at the pion mass of 0.130 GeV/c^2.   Is there a calibration error here?   Seems like a big mis-match.   Then, in the lower panel of the figure (b),  the main bump is centered at about 0.14, just a tiny bit higher than it should be.   Why the discrepancy between the panels?

line 208: use "point-to-point"

Table 1:   maybe put "+-" on the uncertainties quoted.

line 219:  This equation is not looking so good:   it is supposed to express an AMPLTIUDE, but the notation includes a CROSS SECTION which is, by definition, related to an amplitude squared.   Is the notation wrong?   I am sure Misak can clear this up for you (unless I am the one who is confused).

Figure 5:   Here you are plotting, according to the caption, the cross section specifically for the 3pi decay channel.   That is, you seem to be saying it is NOT the full cross section, but only the cross section to the channel of interest.   But that should be about 10% different from the cross section shown in Fig. 4.   To me, the data points (at least the one at most-negative t), look about the same.   Can you clear this up?

That's all for now...

Reinhard