OPT-IN:Exclusive π− Electroproduction off the Neutron in Deuterium in the Resonance Region

[Daniel Carman]

Dear Ralf et al.,

I have read through the draft of your paper on exclusive pion production off the neutron. While
the data is beautiful, the paper is not well written and the lack of polish very much distracts
from the final product. I will try my best to include what I can below from my heavily marked-up
copy. I would welcome the opportunity to reread an updated version as it is possible a second
iteration would be very beneficial to your manuscript. If you have any questions, let me know.

Regards,
Daniel
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General:
 - You are not consistent with your speed of light units throughout. I propose that you set c=1
   throughout.
 - Your notation for the pion angle is inconsistent throughout. Sometimes you use $\theta^*$,
   sometimes $\theta_\pi^*$, and sometimes $\theta_{\pi^-}^*$. I recommend that you do not use
   the last of these as it makes your notation too cumbersome. The same comment applies to
   your usage with azimuthal angle $\phi$.
 - PRC dictates usage of "c.m." instead of "*" for the center-of-mass. You will have to update
   your notation in the text and in your figures.
 - You are inconsistent with your verb tense throughout. For such a manuscript, it is generally
   accepted to use the past tense. I will point this out in my comments below.
 - In your equations and text, trigonometric functions should be in roman font. Use "\sin", "\cos"
   and "\tan" in your equations.
 - You go back and forth with the color "gray" and "grey". Use "gray".
 - The manuscript is written in a "conversational" style for the most part. This leads to
   repetition and language that is not crisp and precise. I will flag the most aggregious
   instances below.
 - As your appendix can be found in many textbooks and published papers, I recommend that you
   remove it altogether and simply give an appropriate reference.
 - Instances of "e.g." should be written as "{\it e.g.}".
 - The usage of "(Color online)" is no longer required. I recommend that you remove it altogether.
 - Your notation of three vectors is awkward when you have momenta with subscripts. You use
   notations such as "\vec{p_s}". I recommend you use "\vec{p}_s" so that the vector symbol is not
   displaced. Please review all three-vector notation in the manuscript.
 - You are not consistent with your use of hyphenation throughout. I will try to point out what I
   flagged in my reading.
 - When you reference equations in the text, sometimes you put the number in parenthesis, and
   sometimes you do not. Be consistent throughout.
 - Quantities and their units are separated across lines. To keep them connect, use a "~". So
   for example, "1.35~GeV" and "0.5~GeV$^2$".
 - Run a spell-checker on the manuscript. There are a number of typos that I caught. I may have
   missed some along the way.
 - In multiple places in the paper you wrote "\sigma_L + \epsilon \sigma_T". Please go through the
   manuscript and fix this.
 - In many of your figures where you have a label of "cos theta_pi$, the pi subscripts are not connected
   to the theta symbol. They float well below it.
 - In your figures where you list the reaction use a proper arrow symbol in the reaction listing instead
   of the awkward "->".
 - Your figure captions have some odd formatting where the text is not evenly space on each line and is
   always left justified. It does not look good.
 - You are inconsistent with your usage of "final-state interaction" and "final state interaction"
   throughout.
 - You are not consistent with your use of Section references. First you should always spell out the
   word "Section" and not use abbreviations. Also, your listings are not consistent. Sometimes you
   have (e.g.) "Section V C" and sometimes "Section V.C".

Page 1:
 - Line 10. Use "... wide final state hadron ...". 
 - Line 11. Use " ... four-momentum transfer squared ...".
 - Line 16. Use "$n \to N^*$".
 - Line 18. Spurious extra space between "available" and "results".
 - Line 23. Use "... protons have been proven ...".
 - Line 37. Use "... [8] has provided the ...".
 - Line 43. Use "... data on the measured observables ...".
 - Line 44. Use "... Physics Database [9].".
 - Line 54. The sentence on lines 54-56 is an orphan. It needs a proper home or it could be dropped
   altogether. But there are two issues with the sentence that I will point out. Use "$\pi N$" instead
   of $N \pi$ to be consistent with your usage throughout the paper. Use "multipoles".
 - Line 57. Use "... have had a considerable ...".
 - Line 68. Use "$\gamma_v pN^*$".
 - Line 74. Use "momentum-dependent".
 - Line 79. Use "$N \to N^*$".
 - Line 82. Use "... the Standard Model ...".

Page 2:
 - Line 95. Use "... that underlie $N^*$ generation ...".
 - Line 101. Use "... between the meson-baryon cloud ...".
 - Line 104. Use "... of the $N(1440)1/2^-$ ...".
 - Line 114. Use "... of the $N(1675)5/2^-$ ...".
 - Line 119. Use "... studies of $N^*$ electroexcitation ...".
 - Line 133. Use "... in addressing these open problems ...".
 - Line 139. Use "$\pi N$".
 - Line 153. Open quotation marks are wrong. Use ``e1e".
 - Line 172. Use "... on the measured cross sections ...".
 - Line 173. This introduction section should end with a bit of an outline to the rest of the paper. It will
   help the reader to appreciate the layout of the paper.
 - Line 175. Use "In the process described in Eq.(1), the initial state ...".
 - Line 181. Use "... of the initial state neutron ...".
 - Line 182. Use "... respectively, which are moving ...".
 - Line 188. Use "... of the reaction in Eq.(1), ...".
 - Line 189. Use "... the initial state proton ...".
 - Line 190. Use "... the interaction; it follows that ...".
 - Line 191. Use "... we can rewrite Eq.(2) as ...".

Page 3:
 - Line 193. Use "... the initial state neutron ...".
 - Line 202. Use "... the initial state proton ...".
 - Line 204. Use "... the reaction of Eq.(1).".
 - Line 206. Use "four-momentum".
 - Line 209. Language is a bit confusing as you have not defined W_i and W_f.
 - Eq.(8). It is not clear what you mean by M_n and m_n. Also use "2~MeV".
 - Line 216. Use "Final state interactions (FSI)".
 - Line 218. Use "... MeV, the quasi-free process, ...".
 - Line 220. Fig. 2 is referenced before Fig. 1 in the text. You should swap the order of the figures.
 - Line 220. Use "... is dominant (see Section IV.B).".
 - Line 224. Use "These processes correspond ...".
 - Line 226. Use "four-momenta".
 - Line 237. Use "... those describing pion electroproduction ...".
 - Line 239. Use "four-momenta".
 - Line 241. Use "... neutron rest frame ...".
 - Line 246. Use "... initial state neutron ...".
 - Line 252. Use "four-momenta".
 - Line 255. Use "Since $\hat{z}_{nrest}$ is ...".
 - Line 257. Use "... as $\cos \theta^*$ and ...".
 - Eq.(9). Second line. Use "... $n$ rest frame$.
 - Fig. 1. Notation problem on incoming electron leg.
 - Line 263. Use "This experiment was carried out ...".
 - Line 265. Use "The CLAS torus magnet ...".
 - Line 266. Use "... naturally separated the ...",
 - Line 267. Use "... CLAS sectors was ...".

Page 4:
 - Fig. 2 caption.
   - Line 1. Use "... sketch of the three ...".
   - Line 2. Use "... impulse approximation, ...".
   - Line 3. Use "$pp$ re-scattering" and "$\pi^- p$ re-scattering".
   - Line 4. There seems to be a spurious space at the start of this line.
 - Line 272. Use "time-of-flight".
 - Line 273. Your discussion of the ECAL is quite awkward and will not be clear to the reader. I suggest a
   few changes to improve this. Start here with "... and sampling-type calorimeters ...".
 - Fig. 3. This figure is not appropriate for e1e. It is for e1-DVCS as you can see with the DVCS solenoid
   on the drawing. Also the LAC is labeled and you never mention it. Also, as you are not reconstructing
   photons in your final state, why choose a picture showing a photon?
 - Fig. 3 caption.
   - Line 4. Use "The tracks shown ...".
   - Line 6. Use "beamline".
   - Line 7. Use "beamline".
 - Line 280. Use "2-cm-long" and "liquid-deuterium".
 - Line 282. Use "... varying from 0.4~cm to 0.6~cm (see Fig. 4).".
 - Line 283. Here you mention the minitorus but have not mentioned it before.
 - Line 283. Use "... +6000~A minitorus current. Furthermore, ...".
 - Line 286. Use "... which were used ...".
 - Fig. 4. I do not think this figure is necessary. It could be removed with no loss of clarity.
 - Line 291. Use "$z$-vertex".
 - Line 295. Use "... to the downstream 15~$\mu$m-thick aluminum exit window, which should be at the same
   position for both ...".
 - Line 299. Use "$z_e$".
 - Line 299. This terminology of "shift-corrected" target is not explained and leaves me confused. I don't
   think you need to mention any of this technical business. It may mean something to you, but is not
   meaningful for the reader.
 - Fig. 5 caption.
   - Line 1. Use "$z_e$".
   - Line 3. Use "$z_e$" and "1.5~mm".

Page 5:
 - Line 303. Use "... candidate required ...".
 - Line 304. Terminology of "negative track" is not explained to the reader. Furthermore the reader will have
   no context for this as you have not explain how charge tracks are bent in the torus field.
 - Line 307. Use "$p_e$". Use "... cut was applied to the electron candidates.".
 - Line 307. The electron threshold cut described in Ref.[51] does not recommend placing the cut at the value
   of the discriminator threshold. It provides a prescription for how far above the hardware threshold setting
   the analysis threshold should be set.
 - Fig. 6 caption.
   - Line 2. Use "... in sector 2, where ...".
   - Line 4. Use"... functions shown by the curves.".
 - Line 312. Use "... the beamline and the CC segments were ...".
 - Line 313. Use "... radially relative to the CLAS polar ...".
 - Line 314. Use "one-to-one".
 - Line 316. Use "... and accidental tracks would not show ...".
 - Line 317. Use "... show such a correlation, as ...".
 - Eq.(10). No vector symbol over momentum z-component.
 - Line 319. Use "The $\theta_{CC}$ cuts shown by the outer lines in Fig. 6 were ...".
 - Line 320. Use ".. data and simulation."
 - Line 322. Use "In order to further reduce contributions from negative pions and other background tracks, cuts ...".
 - Line 324. Use "... 3) were applied ...".
 - Line 335. Use "... was calculated by ...".
 - Line 336. Use "... (see red curves in Fig. 7) defined as ...".
 - Line 339. Use "... factor was determined ...".
 - Line 340. Use ".. each CC segment.".
 - Fig. 7 caption.
   - Line 3. Use "... function in Eq.(12) shown by the red curve.".
 - Line 344. Use "fast-moving".
 - Line 350. Use "... momentum, resulting in much less ...".
 - Lines 351-361. Use instead "Thus the measured deposited energy for showering electrons should be proportional
   to the electron momentum resulting in a constant value of $E_{total}/p_e$ vs. $p_e$. This sampling fraction (SF)
   for electrons is roughly 25\% as shown in Fig. 8. In this analysis $\pm$3$\sigma$ cuts were place on this
   distribution to select the scattered electrons, with separate cut limits determined for each sector for both data
   and simulation."

Page 6:
 - Line 365. Use ".. hadron candidate $i$ and the ...".
 - Line 366. In this section you use a superscript "sc" on multiple variables. Be consistent with your earlier notation
   and use "SC".
 - Eq.(13). The variable "l" is not defined (path length). Also, I do not like the use of "T" for time. Better to be
   consistent and use "t".
 - Line 371. Use "... hadron candidate given by".
 - Line 373. Use "... the electron flight time measured from the SC, ...".
 - Line 380. Use "... which were individually applied on the hadron candidates for each sector.".
 - Line 384. Use "... with low gain photomultiplier tubes were removed from both the experimental data and simulation.".
 - Line 388. Use "... attributed to SC timing calibration inaccuracies.".
 - Line 390. Use "... the affected SC counters [52]."
 - Fig. 9 caption.
   - Line 1. Use "(a) Negative pion $\Delta T$ versus $p_\pi$ distribution. (b) Proton ...".
   - Line 3. Use "... $p_p$ distribution. The upper and lower $\Delta T$ cut limits for sector 1 are shown.".
 - Line 394. Use "... which is therefore not ...".
 - Line 396. Use "... applied to the experimental data.".
 - Line 397. Use "... -012 [53], it is known ...".
 - Line 398. Use "... highest momentum particles.".
 - Line 400. Use "2.039~GeV".
 - Line 402. Use "... be neglected. For the ``e1e" dataset, the elastic peak positions for the six CLAS sectors ...".

Page 7:
 - Line 415. You mention energy loss corrections but do not say how they were determined.
 - Line 423. Use "... mass squared ...".
 - Fig. 10 is really not needed in this paper. You can just state the corrections were at the level of 0.5\%.
 - Fig. 10 caption.
   - Line 2. Use "... $\mu_{M_s^2}$ versus detector ...".
   - Line 9. Use "0.88~GeV$^2$".
 - Line 428. Use "... of CLAS was limited ...".
 - Line 430. Use "... volumes were defined ...".
 - Line 433. Use "... polar angles, as well as momentum, and are different ...".
 - Line 444. Wrong opening quotations on ``e1e".
 - Line 445. Use "... in Ref.[54]."
 - Line 447. Use "sector-dependent">
 - Line 451. Use "$\pi^-$".
 - Fig. 11 caption.
   - Line 1. Use "(Top) $\phi_e$ vs. $theta_e$ distribution of electrons for sector 4 within ...".
   - Line 5. Use "(Bottom) $\phi_e$ distribution for a selected $\theta_e$ bin ($29^\circ < \theta_e < 30^\circ$) for the same
     momentum bin as the top panel."
   - Line 7. Use "... fiducial range."
 - Line 454. Use "... there were additional low-efficiency regions due to dead wires of the DC and bad photomultiplier tubes
   in the SC. These regions, seen in the ... in each sector, were cut out in both data and simulation.".

Page 8:
 - Fig. 12 caption.
   - Line 2. Use "... distributions for $\pi^-$ ...".
 - Line 464. Use "... was determined by".
 - Eq.(16). Here you change your notation for four-vectors compared to what you were using earlier in the paper. I think
   that you should also use lower-case "p" for momentum notation. Review throughout the manuscript as your notation seems
   to change from section to section.
 - Line 467. Use "four-momenta".
 - Line 467. Use "The cut 0.88~GeV$^2$ .... GeV$^2$ (see Fig. 14) was applied for both ...".
 - Line 472. Use "... background, such as two-pion electroproduction, is negligible. See Section VI.E for ...".
 - Line 474. Use "... exclusive event selection".
 - Fig. 14 caption.
   - Line 2. Use "... the red lines showing the ...".
 - Line 477. Use "... reconstructed data as shown in Fig. 16(a).".
 - Line 479. Use "Figure 16(a) shows ...".
 - Line 480. Use "... proton for experimental data (black histogram), simulated data (red histogram), and simulated data
   smeared ... resolution (blue histogram) ...".
 - Line 482. You have mentioned simulation a lot to this point in the paper. However, you have not said anything about
   the simulation package for CLAS or the event generator that you employed.

Page 9:
 - Fig. 15 is placed out of order. It should go after Fig. 17.
 - Fig. 15 caption.
   - Line 2. Use "(black histogram)"
   - Line 3. Use "(blue histogram)"
 - Line 485. Use "... momentum distribution that is smeared according to the experimental ...".
 - Line 487. Use "... distribution almost perfectly. There is no meaningful difference between ...".
 - Line 489. Use "... simulated (blue histogram) and measured (black histogram) ...".
 - Line 492. Use "... the simulated (red histogram) and measured (black histogram) ...".
 - Lines 494-500. This text reads as gibberish to me. It needs attention to present things clearly.
 - Line 502. The unit is "keV".
 - Eq.(8). All this talk about colors (green and red) is kind of meaningless before presenting Fig. 15.
 - Line 509. Use "... represents the simulated ...".
 - Line 510. This superscript is really very awkward. There has got to be a better notation.
 - Line 513. Use "... areas shown in Fig. 15 represent ...".
 - Fig. 16 caption.
   - Line 1. Use "The black histogram represents ...".
   - Line 5. Use "... distribution is shown by the red histogram and the detector-smeared Monte Carlo distribution by the
     blue histogram.".
 - Line 517. You have lots of use of "MAID" and "SAID" but you have said nothing about what these models are. Without a
   few words to the reader, the comparisons are not meaningful. I think you need a few sentences of introduction in the
   paper instead of just pointing to references.
 - Line 523. You need a reference to "aao_rad".

Page 10:
 - Fig. 17. It is not clear what this figure is showing.
 - Line 527. Use "Even though MAID2007 is ...".
 - Line 532. Use "... bin centering corrections.".
 - Line 533. Use "$en \to e'p\pi^-$". Your prime symbol seems to be way above the "e".
 - Line 535. Use "... were generated by ...".
 - Line 537. Use "... mass was set to ...". Use "... prootn was generated ...".
 - Line 540. Use "... proton behaved like ...".
 - Line 542. Use "... process could be treated ...".
 - Fig. 18. I cannot distinguish between the red and magenta curves. Also, you should remake this plot zooming in the
   x-axis to where the data is.
 - Line 549. Use "... Tables I and II."
 - Line 556. Use "... bin sizes were studied as listed in Table II." Is this study mentioned again anywhere?
 - Line 557. Use "However, this does not solve the empty cell problem and ...".
 - Line 558. Use "... different bin choices ...".
 - Lines 559-561. I have no idea what you are trying to say here.
 - Line 560. Use "... allows for the optimization of the ...".
 - Table II. I would complete the last three rows of the table into one row, listing the different bin sizes in the
   final column.
 - Line 564. Use "... section across a bin.".
 - Line 567. Use "To account for this effect, a correction was applied ...".
 - Line 569. Use "4-dimensional". There is a notation problem in your bin listing.
 - Line 570. Use "... was calculated as".
 - Line 573. Use "... each kinematic bin and ..."

Page 11:
 - Line 578. Use "... were calculated using ...".
 - Line 580. Use "... statistical fluctuations) ...".
 - Line 583. Use "... that were generated ...".
 - Line 584. Use "... radiative effects turned on in each ...".
 - Fig. 19 caption.
   - Line 1. Use "... for the measured ...".
   - Line 2. Use "... (black histogram) ... (blue histogram) data, as well as the ...".
   - Line 3. Use "... events (magenta histogram). The $M_s^2$ cut region is shown by the vertical lines.".
 - Line 594. Use "Although these effects do not influence the kinematic ...".
 - Line 597. Use "... [59] was used to ...".
 - Line 598. Use "The same number of $en \to e'p\pi^-$ events with ... were generated by ...".
 - Line 603. Use "... $RC$ was calculated by ...".
 - Line 607. Use "Finally, $RC$ was combined with the acceptance correction factor $A^{Rad}$ (see Eq.(21)) ...".
 - Line 609. Use "radiative-corrected".
 - Line 610. Use "... $A_{RC}$, represented by".
 - Eq.(23). Notation issue in second line. Use "RC", not "RC_{correct}".
 - Line 612. Use "... p \pi^+ \pi^-$ ..." (Consistently list the reaction in same way throughout the paper.)
 - Line 621. Use "... p \pi^+ \pi^-$ ...".
 - Line 623. Use "... bin-by-bin ... with the simulated ...".
 - Line 625. Use "... in the background contribution [52].".
 - Line 633. Use "... all sources studied and the magnitudes ...".
 - Line 635. Use "... of the cross sections is ...".
 - Line 636. Use "... calculated as the quadrature sum of the ...".
 - Line 637-639. This seems like a random statement. Better to try to make a more general assessment rather than
   make a very specific statement here. Also note the notation issue where "cos" and "theta" are split over multiple
   lines.
 - Line 640. Use "... systematic uncertainty is ...".
 - Line 641. What do you mean by inclusive cross section here? $en \to e'X$ or something else?
 - Line 646. Use "... checked against the systematic uncertainty of the quasi-elastic ...".

Page 12:
 - Table III caption.
   - Line 2. Use "systematic uncertainty".
 - Table III entry. Use "bin centering correction".
 - Line 647. Use "... in nuclei [64]. We found that the world data and the normalized ...".
 - Line 652. Use "Osipenko-derived".
 - Line 656. Use "acceptance-corrected".
 - Line 658. Use "... represent the number of exclusive events ...".
 - Line 661. Use "LD$_2$".
 - Line 663. Use "... was calculated from ...".
 - Line 665. Use "... LD$_2$, which was calculated ...".
 - Line 667. Use "... the bin centering correction factor $R_{BC}$ was calculated ...".
 - Line 671. Use "live-time".
 - Line 673. Use "liquid-deuterium".
 - Line 677. Use "... section was calculated ...".
 - Line 683. Use "... section was extracted ...".
 - Line 685. Use "... that were calculated ...".
 - Line 686. Use "radiative-corrected".
 - Line 687. Use "... ) was calculated analogously to Eq.(23) ...".

Page 13:
 - Eq.(29). Notation issue in numerator and denominator for "\phi_\pi".
 - Line 690. Use "... quantify the kinematically ...".
 - Line 691. Use "two-fold".
 - Line 694. Use "... the exclusive $\pi^- p$ electroproduction structure functions ...".
 - Line 695. Use "... $\sigma_{LT}$ and their Legendre moments and explore their ...".
 - Line 699. Use "... quasi-free contributions"
 - Line 704. Use "... region (see Section IV.B). However, for ... 200~MeV, FSI contributions ...".
 - Line 705. Use "... become larger with increasing $p_s$.".
 - Line 710. Use "... only on the experiment data.".
 - Line 718. Use "... final state interactions ...".
 - Line 725. Use "... that describe FSIs for the ...".
 - Line 726. Use "... with a deuteron target ...".
 - Line 733. Use "... Physics Database ...".
 - Line 734. Use "... for the exclusive $\pi^- p$ electroproduction differential cross sections ...".
 - Line 739. Use "... from the SAID [65,66] and ...".
 - Line 746. Use "... available data that was ...".
 - Line 749. Use "... $\phi^*$ of these older data, together with their substantial uncertainties, prevented the
   extraction of physics information from these data. Our measurements ...".
 - Line 754. Use "... \cos \theta^*$, nearly complete coverage ...".
 - Line 756. Use "... in some $(W,Q^2,\cos \theta^*)$ bins ...".
 - Line 757. Use "... overall statistically meaningful cross ...".
 - Line 760. You use a 2% relative uncertainty cut-off? This seems to me a waaaay too conservative choice. How has
   this draconian choice affected your coverage and your number of discarded kinematic bins. I think some motivation
   for this choice is needed here.
 - Line 762. Use "... cross sections in all ...".
 - Line 763. Use "In fact, the quasi-free ...".
 - Line 764. Use "... to the full cross ...".
 - Line 775. Use "... the measurements reported here demonstrates ...".

Page 14:
 - Fig. 20, 21, and 22 captions. You state "The gray shaded regions represent the corresponding systematic
   uncertainties.". I do not see gray shaded regions in the figures.
 - Line 787. Use "... electroproduction were determined ...".
 - Line 788. Use "... mechanism [68] and by fitting the ...".
 - Line 791. Use "... to".
 - Line 792. Do not indent this line.
 - Line 800. Use "... achieved using Eq.(31) shown for representative bins in Figs. 23-25 by the black and green
   dashed lines, support a reliable extraction of the fully exclusive, as well as the ...".
 - Line 806. Use "... from our results, can be found in the CLAS Physics Database along with the differential
   cross sections (6475 ...)". By the way, this is the third time that you have mentioned that the data is in
   the CLAS Physics Database. I think once would be sufficient.
 - Line 813. Use "... in Fig. 26, together with ...".

Page 15:
 - Line 816. Use "... of the fit parameters in Eq.(31)."
 - Line 817. Use "... in some $(W,Q^2,\cos \theta_\pi^*)$".
 - Line 820. Use "... are not well constrained, which can lead to large uncertainties of the fit parameters.".
 - Line 823. I would start a new paragraph with the sentence "The most prominent ...".
 - Line 831. Use "... contributions or coupled-channel effects related ...".
 - Line 833. Use "... with the $\eta n$ channel that ...".
 - Line 837. You state that the models are very different from the data in the second and third resonance region.
   I would argue that the agreement is pretty good at W=1.7 GeV. Please review your language here and use crisp
   and accurate statements.
 - Line 840. Use "... our results provide new information ...".
 - Line 845. Use "... structure function for ...".
 - Line 847. Use "... in Fig. 27 compared to the interpolated ...".
 - Line 848. Use "... function of $\pi^+n$ electroproduction ...".
 - Line 851. Use "Here, $\pi N$ ...".
 - Line 854. Use " pion CM angles, the ...".

Page 16:
 - Line 863. Use "... of quasi-free $\pi^- p$ electroproduction ...".
 - Line 864. Use "... to that of $\pi^+ n$ electroproduction ...".
 - Line 865. The statement "This expectation is reflected in the results of our measurements as demonstrated
   in Fig. 27.". But the agreement is clearly very poor at forward angles. I think you need to revisit your
   discussion to accurately reflect what you have shown. I am also confused about how the statements made in
   lines 8666 to 873 follow from this statement. Please review.
 - Line 878. Use "... bin were decomposed ...".
 - Line 881. Use "... to Eqs.(32)-(34), ...".
 - Line 885. Use "... GeV within the covered $Q^2$ ...".
 - Line 893. You have just talked about lot of details of the Legendre moments in lines 875-892. Only at line
   893 do you actually introduce the form of the expansion. The order seems in appropriate to me. I should
   think that you would first introduce the form of the expansion and then go into the details.

Page 17:
 - Figs. 23, 24, 25 captions.
   - Line 1. Use "Fully exclusive ... $\mu$b/sr for $W=1.6625$~GeV ...".
   - Line 2. Use "... are shown in each ...".
   - Line 3. Do not put quotations around the functional form.
 - Line 902. Use "... already provides a reasonable description of the unpolarized structure function for
   $\pi^-p$, but fails to ...".
 - Line 908. The sentence "Different truncations should be employed for different structure functions."
   does not follow from the text above. You just said that using lmax=2 works for all structure functions.

Page 18:
 - In the captions of Figs. 24 and 25, the magenta points are not mentioned. This should be rectified.
 - Line 912. Use "... dependencies were computed ...".
 - Line 914. Use "... of the $\Delta ...".
 - Line 922. Use "... from the $\Delta ...".
 - Line 923. Use "... off the $\Delta(1232)3/2^+$ affects the ...".
 - Line 924. Use "... in the entire kinematic range covered by the measurement.". Drop the sentence "This
   behavior is observed ... 1.0~GeV$^2$."/
 - Lines 926-932. I cannot make sense of this rambling verbiage. Please review and make a crisp statement.
 - Line 932. Use "Owing to isospin invariance, the ...".
 - Line 937. Use "... of the $(e,e'X)$ ...".
 - Line 934-938. Are you trying to say that the presence of the Delta(1232) in your data is some kind of
   a surprise? That sure seems like what is written to me.
 - Line 943. Use "... $W$ dependence of the ...".
 - Line 944. Use "The $N(1440)1/2^+$ in $\pi^- p$ ...". You do not need to keep repeating the word "resonance"
   every time you list a state.
 - Lines 947-955. These sentences use a lot of words but do not make a crisp point. It reads like
   a stream-of-consciousness flow. Please revisit and sharpen the text. I would suggest something if I had
   a clue what point you were trying to aim at.

Page 19:
 - Line 958. Use "... contributions to the $\sigma_{LT}$ ...".
 - Line 965. Use "... since there are no available experimental results ... off bound neutrons,
   the ... "
 - Line 970. Use "... from the $\pi^-p$ differential cross sections presented here."
 - Line 977. Use "$(W,Q^2)$"
 - Line 983. Use "... the measured observables. The FSI contributions in this kinematic region for
   $\pi^-p$ electroproduction are about 10-20\% on average. The azimuthal angle dependence of the
   extracted ...".
 - Line 988. Use "photon-polarization-dependent".
 - Line 991. Use "model-independent".

Page 20:
 - Fig. 26 caption.
   - Line 3. Use "... that were extracted ...".
   - Line 4. Use "... the fully exclusive ...".
   - Line 6. Use "$y$-axis". Use "The data are compared ...".
   - Line 10. Use "... is described in Section VIII.C.
 - Line 995. Use "... from the $\Delta ...".
 - Line 996. Use "... dominates, further supporting the reliable evaluation of the quasi-free cross sections.".
 - Line 1007. Use "$n \to N^*$".
 - Line 1013. What do you mean by "missing-proton topology". Some explanation is needed here.
 - Line 1013. Use "... which aims to extract the quasi-free $\pi^- p$ electroproduction ...".
 - Line 1016. Use "... impact of the relatively small fully exclusive final state acceptance in CLAS12 [49]".
 - Line 1025. Use "JLab".
 - Line 1027. Use "$n \to N^*$".
 - Acknowledgments. JLab requires a standard acknowledgment that includes the JLab DOE contract number. You
   can embellish this with other things, but you need the official part.
 - Line 1040. Use "... reaction with an unpolarized electron beam off unpolarized ...".
 - Eq.(A2). Add a space between equation and "and".
 - Line 1045. Use "... where $E$ is the electron beam energy, and $E'$ and $\theta_e$ are the ...".

Page 21:
 - Fig. 27. On the y-axis your font choice is distorted. The epsilon symbol overlaps your sigma_L.
   arrow in the reaction listing instead of the awkward "->".
 - Fig. 27 caption.
   - Line 2. Use "... that were extracted from the fully exclusive ...".
   - Line 2. Use "... cross sections for $W < 1.35$~GeV compared with ..."
   - Line 3. Use "... CLAS results on the $\pi^+n$ ...".
   - Line 3. Typo on "electroproduction".
   - Line 4. You mention that the gray bars represent the systematic uncertainties, but
     for which data. In fact, there are systematics for each of the magenta, green, and
     black points that need to be understood to make the most of this data comparison.
   - Line 5. Use "... bars is desribed in Section VII.C.".
 - Line 1054. Use "four-fold".

Page 22:
 - Fig. 28. The bottom row of plots should have y-axis labels of "\sigma_{LT}" not "\sigma_{TL}" for
   consistency of notation,
 - Fig. 28 caption.
   - Line 3. Use "... that were extracted ...".
   - Line 4. Use "... (red line), ...".
   - Line 5. Use "... systematic uncertainties of the data.".
   - Line 5. Use "... expansions were fit to the corresponding ...".
   - Line 6. Use "... up to $l_{max}$=1 ... and $l_{max}$=2 ...".

Page 23-25:
 - Fig. 29-31 captions.
   - Line 1. I suggest "... up to $l_{max}$=2 at ...".
   - Line 3. Use "$y$-axis".
   - Line 3. Use "The data are compared ... MAID2000 [67] models."
   - Line 3. Use "The solid lines represent the ...".
   - Line 6. Use "... systematic uncertainties of the data.".

References:
 - The references are not in a standard form. As an example for your first reference the APS style guide
   would give: I.G. Aznauryan and V.D. Burkert, "Electroexcitation of Nucleon Resonances", Prog. Part.
   Nucl. Phys. {\bf 67}, 1 (2012).
 - You should just list the first page number of the published paper, not give a page range. Besides you
   do not handle this consistently throughout.
 - Your are not consistent with your capitalization of the journal titles throughout.
 - Ref. [50] is a repeat of Ref. [8].
 - You use "PhD". Instead it should be "Ph.D.".
 - Ref. [61]. Use "JLab".