[Clascomment] OPT-IN:Cross sections for the gamma p --> K* + Lambda and K *+ Sigma 0 reactions measured at CLAS

[Daniel Carman]

					                 January 15, 2013


Dear Wei and Ken,

I have read through your paper on the K*+Y cross sections. I included my comments below.
Nice to see this work coming to publication. If you have any questions, let me know.


			   Regards,

				  Daniel

********************************************************************
Page 1.
 - Abstract.
   - Line 6. Use "... and a Regge model, ...".
 - Right column.
   - Paragraph 4.
     - Line 7. I think a better way to say this is "... beam incident on a 1$\times$10$^{-4}$
               radiation length gold foil.".

Page 2.
 - Left column.
   - Paragraph 3.
     - Line 17. The CLAS momentum resolution is only about 1%. 0.1% is not possible.
     - Line 21. I suggest "... outermost drift chambers at a radius of about 4~m from the target
               and was used ...".
   - Paragraph 4.
     - Line 6. Use "kHz".
   - Paragraph 5.
    - Line 1. Use "datasets".
 - Right column.
   - Table I caption should end in a period.
   - Paragraph 2. 
     - Line 2. Use $K\pi$.
   - Paragraph 3.
     - Eq. 3. Remove "+" between the particle types for consistent notation.
   - Paragraph 4.
     - Line 2. Use "... while the $\Lambda$ and $\Sigma^0$ are reconstructed ...".
   - Paragraph 5.
     - Add a comma at the end of Eq. 4 and Eq. 5.
   - Table II second row should have particle types in math mode. e.g. $K^0\pi^+$.
   - Last line before Eq. 5. Use "momentum $p$".


Page 3.
 - Left column.
   - Paragraph 1.
     - Line 2. Use "... scintillators and $t_{sc}$ is the time when the photon hits the target. This
               information ...".
     - Add a comma at the end of Eq. 6 and Eq. 8. Add a period at the end of Eq. 7. Change the "and"
       after Eq. 6 to "where". Change the "or" after Eq. 7 to "Thus".
     - Last line. Use "... bunch structure of CEBAF.".
 - Right column.
   - Paragraph 1.
     - Line 1. Use "$\vert \Delta tof \vert \< 1.0$~ns".
   - Paragraph 2.
     - Line 6. Use "... various cuts was tested with ...".
   - Paragraph 3.
     - After the third bullet point, I recommend that you go back to normal paragraph form without the
       minipage construct here.
     - Eq. 10 should not have the "+" symbols between the particles for consistent notation.

Page 4.
 - Left column.
   - Paragraph 1.
     - Line 3. Use "... peak impossible. On the other hand, ...".
     - Line 9. I suggest that you drop the bit "whereas a different approach (given below) ... production.".
               This is all a repeat of what you just said and adds nothing.
     - The statements made regarding the background beneath the Lambda and Sigma0 made here confuse me.
       Fig. 3d shows that the background beneath the Lambda is smaller than for the Sigma0. Why not just use
       hyperon templates with a polynomial background to extract the yields?
   - Section E. Your usage here of sideband subtractions is non-standard. A sideband subtraction is typically
                performed when the background beneath the peak is linear. Here, as seen in Fig. 2, that is
                most certainly not the case. A sideband subtraction as you are employing here will most
                certainly underestimate the background contributions if you average the L and R sidebands.
                I think that a statement in the paper as to what you are trying to accomplish here is
                called for.
   - Paragraph 2 of Section E. 
     - Line 6. Use "$K_S$". Line 9. Use "$K^0$".
 - Right column.
   - Fig. 2 caption.
     - Line 1. Use "... invariant mass showing the $K_S$ ...".
     - Line 2. Use "distribution.".
   - Paragraph 1.
     - Line 1. Use "M(\pi^+\pi^+\pi^-)$.
     - Line 3. Use "$K^{*+}$".
     - Last sentence. You mention 3-body phase space. What about the contributions of simple 4-body
                      phase space for the 3piLambda final state?
     - Line 12. Use "$K^0\pi^+\Lambda$".

Page 5.
 - Left column.
   - Paragraph 3.
     - Line 4. Use "... leakage there is to the $K^^{*+}\Sigma^0$ reaction channel.".
 - Right column.
   - Paragraph 1.
     - Line 10. Use "$K^*$".
   - Paragraph 2.
     - Line 6. Use "... for other CLAS analyses of this same dataset [18].".

Page 6.
 - Left column.
   - Fig. 4. Showing fits of this sort is fine for a qualitative cross check, but you should state what the
             average reduced chi**2 is for your fits. What is shown in the top part of Fig. 4 looks like it
             does not fit the background away from the peaks very well.
   - Fig. 4 caption. Line 3. Use "... contributions from the ...".
 - Right column.
   - Add commas after Eq. 11 and Eq. 13.
   - Paragraph 2.
     - Line 1 after Eq. 12. Use "... $K^{*+}$ peaks for the ...".
   - Eq. 13. You have some notation inconsistencies. Throughout this paper you use three different
             angular notations. 1). cos theta, 2). cos theta_K*+^CM, 3). cos theta^*. Pick one and use
             it consistently.
   - In the paragraphs after Eq. 13, all of your symbols should be in math mode. e.g. $Y$, $N_{target}$,
     $N_{gflux}$, $f_{lt}$. Please review this and catch all of these.

Page 7.
 - Left column.
   - Add commas after Eq. 14, Eq. 17, and Eq. 18.
   - Please put all of you symbols in math mode.
   - Add a space before the units of Eq. 16.
   - Line 2 after Eq. 15. Use "... of each CLAS run), while ...".
   - Section V paragraph 1.
     - Line 1. Use "Fig. 6 shows ...".
     - Line 2. Remove "+" symbols between particle types for consistent notation. Reaction should be
               written in math mode.
     - Line 3. Use "... for $E_\gamma$ bins ranging ...".
     - Line 6. Put reaction in math mode.
     - Line 7. Use "$t$-channel" here and throughout. Also fix all "$s$-channel" throughout.
     - Line 8. Use "Similarly, Fig. 7 shows ...".
     - Line 9. Remove "+" symbols between particle types for consistent notation. Reaction should be
               written in math mode.
   - Section V paragraph 2.
     - Line 3 after Eq. 18. Use "$a_0$".
     - Line 4 after Eq. 18. Add a period at the end of this sentence.
 - Right column.
   - Paragraph 1.
     - Line 1. Use "Fig. 6 shows ...". Remove "+" symbols between particle types for consistent notation. 
               Reaction should be written in math mode.
     - Line 2. Use "... channel and Fig. 7 shows the fits for the ...". Remove "+" symbols between particle 
               types for consistent notation. Reaction should be written in math mode.
     - Line 3. Put symbols in math mode.
     - Line 5. Use "... $E_\gamma$ in Fig. 8.".
     - Line 6. Use "... shown in Fig. 9 ...".
   - Paragraph 2.
     - Line 2. Use "... cut parameters, ...".
   - Paragraph 3.
     - Line 1 after Eq. 19. Use "histogrammed".
     - Line 2 after Eq. 19. Remove "(twice)". It adds nothing.
   - Last paragraph.
     - Line 2. Use "effective Lagrangians".
     - Line 3. Use "Reggeized". Check for proper capitalization throughout.

Page 8.
 - Fig. 6 caption. Use "Fitting the differential cross sections for $\gamma p \to K^{*+}\Lambda with ...".
 - Somewhere note that your cross sections are bin averaged and you present the bin averaged results at the
   geometric center of the angle bin.
 - Please add a note explaining the horizontal and vertical error bars in your results section so the reader
   can know what they are.
 - You sometimes use "O-K Model" and sometimes use "O-K model". Be consistent with your usage throughout.
 - Right column.
   - Line 6. Put particle symbols in math mode.

Page 9.
 - Right column.
   - Line 4. Use "Fig. 10 shows ...".
   - Line 6. Use "... from the O-K ...".

Page 10.
 - Fig. 8 caption. Use "... $E_\gamma$ for the $\gamma p \to K^{*+}\Lambda$ (left) ...".
 - Fig. 9. Increase the font size on the plot keys.
 - It is not clear why you only show calculations for the K*+Lambda final state and not for the
   K*+Sigma0 final state. Then you have calculations for the ratio. Please make it clear why this
   is the case.
 - The purpose of showing the total cross section ratio is not clear. You give some reasoning in the
   conclusion section but not here. This is necessary to tell the reader why you are doing this. These
   are different reactions with different associated dynamics, i.e. different resonant and nonresonant
   contributions. A ratio does not seem like such a meaningful thing to study.
 - Right column. Line 5. Typo on "form" when you mean "from".

Page 13.
 - Fig. 11 caption. Line 4. Use "dotted".

Page 14.
 - Put the references in the order cited. It looks like Ref. 17 is out of order.
 - Your bibliography style is not consistent throughout. Inconsistent use of italics and commas.
 - Refs. 12, 13, 14, 15, and 16 are not CLAS Collaboration papers. They were published with only the
   names of the folks who worked on the subsystems.
 - Is there a corresponding URL for Ref. 19?