[Clascomment] OPT-IN: Tensor Correlations Measured in 3He(e,e′ pp)n
Daniel Carman
carman at jlab.org
Sat Jul 10 12:44:00 EDT 2010
July 10, 2010
Dear Larry et al.,
I have read through the draft of your correlations paper. To be honest,
I do not think that this paper meets the threshold for \"general interest\"
needed for acceptance and publication in Phys. Rev. Lett. I just don\'t
think that the discussion really makes a clear statement of what is so
important or interesting here. The big conclusion seems to be that
tensor correlations are important to describe this data. But you have
not said anything general enough to tell me why anyone should care about
this finding. Also, while th first 2.5 pages were readable and
understandable, I found the second half of the paper to be to \"jargony\"
and specialized for me to follow.
Anyway, this is just my opinion. Take it for what it\'s worth. I will
support your journal submission decision. My specific comments on the
manuscript (dated July 2, 2010) are given below. Let me know if you have
any questions.
Regards,
Daniel
*************************************************************************
General.
- I recommend you use c=1 units throughout this paper. Your usage of
units is not consistent.
Page 1.
Right Column.
Paragraph 2.
Line 8. Use \"$^{12}$C\".
Paragraph 3.
Line 3. I find this sentence awkwardly written. How about \"... of
other effects, including Final State Interactions (FSI) and
two-body currents such as meson exchange currents (MEC) [14], which
add coherently to the correlation signal.\".
Line 7. Use \"two-body current\".
Line 8. Use \"... 2m\\omega > 1$, where $Q^2$ ...\".
Line 9. Use \"... transfer, respectively.\".
Page 2.
Left Column.
Paragraph 2.
Line 3. Use \"5-cm-long\".
Paragraph 3.
Line 1. I prefer \"CLAS uses a ...\".
Line 1. Use \"in-bending\".
Line 5. The statement that momentum coverage extends down to
0.25 GeV for protons is kind of misleading/confusing. It extends
down to a value where the protons make it through CLAS to the
TOF (above ADC threshold or perhaps trigger threshold) and where
we have confidence that we can account for energy loss corrections.
So, your value is somewhat arbitraryly chosen, but you make it
sound like a true threshold for CLAS, which it is probably not.
Line 14. You say that you relied on comparing your extracted elastic
cross section to the world\'s data. I think it is appropriate to
state quantitatively the level of this agreement. Also, comparison
of elastic cross sections is not fully appropriate to tune up your
acceptance/efficiency corrections for CLAS because your multi-
particle final state includes particle correlations that affect
reconstruction and trigger efficiency. These effects are not in
the elastic channel. Comments?
Paragraph 4.
Line 7. You state that Fig. 1 (right) shows the missing mass
resolution. You have said nothing about the resolution as no
fit is shown.
Fig. 1 caption.
Line 1. Use \"vs.\".
Right Column.
Fig. 2 caption.
Line 1. This is really not a \"Dalitz plot\".
Line 1. Use \"vs.\" instead of \"versus\" for consistency.
Paragraph 1.
Line 6. Your statement about \"upper right half of the plot\" is
confusing. Where exactly are we supposed to be looking? I think
you should be explicit and say events for which $T_{p1}/\\omega
+ $T_{p2}/\\omega > 1$.
Line 9. The sentence \"There are three peaks at the three corners
... where two nucleons each have less than 20% ...\" is kind of
(sort of) speculative without seeing the correlation with the
$T_n/\\omega$ axis.
Paragraph 2.
Line 1. Use \"We then looked at the opening angle ...\".
Line 6. Use \"... simulation that assumes three-body ...\".
Paragraph 3.
Line 5. The cut on p_perp < 0.3 GeV seems kind of arbitrary. Any
motivation to share for this choice?
Line 7. The sentence \"These paired nucleons are distributed almost
isotropically in angle ...\" is unclear. You just said that the
paired nucleons are peaked at 180 deg, as seen in Fig. 2 (right).
What am I missing here?
Page 3.
Left Column.
Paragraph 2.
Line 3. Use \"... in Figure 3, along with ...\".
Line 9. You state a systematic of 15%. I would like you to add a
bit more here and at least state what the major/dominant source
of systematic were and their contribution to the total uncertainty?
Fig. 3 caption.
Line 4. Provide a reference in the caption to the Golak work.
Paragraph 3.
Line 1. I found the first sentence confusing because I did not know
if you were trying to discuss both the pp AND pn pairs or just
the pn pairs. I believe you are trying to talk about the pn pairs.
Thus I would suggest \"For the $pn$ pairs, the $p_{rel}$ ...
0.7 GeV. The associated $p_{tot}$ distribution for the $pn$
pairs rises ...\".
Right Column.
Paragraph 3.
This was the point in the paper where I think things started to
get very \"for experts only\" and I started to get lost.
Line 1. You start to discuss the calculation by Laget, but you do
not show the results of his calculation anywhere. Also, I don\'t
think describing the Laget calculation as a \"diagrammatic approach\"
really tells me anything about this calculation. I have no idea
what to make of this.
Line 6. The two sentences beginning \"The $pp$ pair momentum distributions
... in as $p_{tot}$ increases.\" mean nothing to me. I have no
idea what you are trying to say.
Line 12. Also, you do not make it clear what \"large\" means when
discussing the level of three-body contributions in the Laget
calculation. What does \"large\" mean relative to the full cross
section and the two-body contribution?
Paragraph 4.
Line 1. You state a ratio of pp to pn pair cross sections of 1 to 4.
I don\'t see how this follows from Fig. 3. It looks like 1 to 2 or
1 to 2.5. How did you determine this value?
Paragraph 5.
Line 7. What does \"relatively low $p_{tot}$\" mean?
Paragraph 6.
Line 8. I suggest \"... increases to $sim$0.4 to 0.6 for ...\". Your
value of 0.5 disagrees with Fig. 4.
Line 9. The sentence \"The ratio rises much faster than the ...
calculated from the bound state wavefunction.\". I have no idea
what this means.
Line 13. Use \"... 0.4 - 0.6$ at large ...\".
Page 4.
Fig. 4 caption.
Line 3. Provide a reference in the caption to the Golak paper.
Line 5. What is the dashed calculation here? I have no idea what this
means based on what you have provided.
Left column.
Paragraph 2.
Line 1. Why should I care about tensor correlations? You need to
provide some appropriate discussion on this point.
Line 2. \"At low $p_{tot}$, the $pp$ pairs are in an $s$-state ...\".
Based on what? Is this an assumption or do you have something
to back this up?
Line 4. \"Due to the tensor interaction, the $pn$ pair does not
have this minimum.\". I have no idea what this means. Is this
a general feature that can be explained or some model-dependent
point?
Line 9. Again, you use the very loose terminology \"large contributiom\".
See my earlier comment on this point.
Paragraph 3.
I found this entire paragraph to be \"loosely\" written. I am not
sure that it made a clear, crisp point.
Line 4. Use \"... only one other nucleon.\".
Line 16. Provide a reference to the Laget prediction.
Right column.
Paragraph 1.
Line 10. Use \"... approximately 0.6 at ...\".
Last sentence. Again, I am not sure why this is important.
References.
- Why do you include a preprint number for published papers? I don\'t
think this is appropriate.
- Refs. [12], [26], [28] are not in standard format. Also, get rid of
the URL.
- With Ref. [12] you list a collaboration. You do not do this consistently
for the other papers, notably the CLAS Collaboration papers.
- Ref.[19] should be \"B.A. Mecking et al.\".
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