[Clascomment] OPT-IN: First Exclusive Measurement of Deep Virtual Compton Scattering off 4 He: Toward the 3D tomography of nuclei

[Barry Ritchie]

Very nice article. I have the following corrections/suggestions:

1. Fig. 1 caption: “leading-order”

2. Line 51: Abbreviate the word “Figure”: “Fig. 1”

3. Line 93: Use “CEBAF Large Acceptance Spectrometer (CLAS)”

4. Line 110: Father than “very high rate background” use “large background”
 
5. Line 111: Use MKS abbreviation: “5-T solenoid magnet”

6. Line 115: “low-energy”

7. Line 129: “\^{C}erenkov”

8. Lines 142-143: Ambiguous reference and misspelled word. I suggest “These soft photons do not affect directly our measurement, …”

9. Line 153: Remove parentheses in definition: “coplanarity angle $\Delta \phi$...”

10. Line 156: Remove parentheses in definition: “and the angle $\theta$ ...”

11. Fig. 2 caption: End of last sentence, some missing hyphens and some ambiguity, so I’d suggest changing to “…top to bottom are: coplanarity angle $\Delta \phi$, missing energy $E_X$, missing-mass-squared $M_X^2$, and the cone angle $\theta$ between the measured photon and the missing momentum of the $e^\prime$He$^\prime$ system."

12. Fig. 3 caption: Just to remove any unambiguity, I’d suggest: “Coherent DVCS event distributions for $Q^2$ after exclusivity cuts. The distributions are shown as a function of Bjorken variable $x_B$ (left) and as a function of squared-momentum transfer $–t$ (right).”

13. Line 188: The use of the word “it” is almost always ambiguous, as is the case here – you discussed two contributions in the previous sentence. Be explicit: “However, the effect of BH [I think?] is enhanced in the observables…”

14. Lines 204-205: Remove unneeded parentheses and remove “it” construction: “Using the different $\sin \phi$ and $\cos \phi$ contributions, both imaginary and real… can be extracted unambiguously.” (Note: I think the word you want is “unambiguously” rather than “unequivocally”.)

15. Line 233: Clarify what the number represents “ cuts (8\% systematic uncertainty)

16. Fig. 4 caption: Just to aid the reader, I suggest “… as a function of azimuthal angle $\phi$.”