We thank colleagues who have given detailed feedback and suggestions on version 5b of the manuscript.  We have addressed all comments in this file: drupal.star.bnl.gov/STAR/system/files/ResponseToCommentsV5b.pdf

The manuscript has been substantially revised and improved as a result of this feedback.  A colored mark-up showing what has been removed and added may be found here: drupal.star.bnl.gov/STAR/system/files/LambdaPolarizationNature_v6_OldAndNew.pdf

and the manuscript with just the final text may be found here: drupal.star.bnl.gov/STAR/system/files/LambdaPolarizationNature_v6_JustNew.pdf

---

------------------------------------------------------------------------------------

Thank you very much to the Godparent Committee, Declan Keane (chair), Bill Llope (PWGC rep), Huan Huang, Evan Finch, Xu Sun.  After several iterations, please find the manuscript here:

 

The only difference between this and NatureV5 is a spelling correction (nannodroplets --> nanodroplets) and removing "like an ideal non-interacting gas." in line 172, both suggestions of Declan.

We look forward to your comments.
The PAs: Isaac Upsal, Mike Lisa, Sergei Voloshin

Analysis Note: https://drupal.star.bnl.gov/STAR/blog/iupsal/lambda-polarization-cumulant-method-analysis-note

Paper proposal: https://drupal.star.bnl.gov/STAR/lambda-polarization-prc-paper-proposal

The GPC approved version 3 of this paper, but there have been small corrections to the data in Figure 4, which are explained in the following two paragraphs:

The first thing:  As has been discussed in bulkcorr and described in the analysis note, the Lambda topology cuts depend on whether or not the daughters have TOF information - thus one set of cuts is used if (for example) the proton track has TOF information and the pion does not. As part of the systematic errors study it was determined that the polarization from one such "class" of Lambdas, where the pion has TOF information but the proton does not are especially sensitive to variations of the topology cuts. Since this class of Lambdas comprised only a few percent of the sample it was decided that we would not use them in the analysis note. I had not since rerun all of the data to do this. Therefore the figure in all previous draft versions of the paper included these Lambdas.

The second thing:  We initially did not plan on using 15GeV in the analysis so it was run differently from the rest of the energies. 15GeV running requires a unique RVertex cut which was not included correctly in the event plane correction histograms I used for that datapoint. The event plane corrections have since been rerun so you may notice a larger difference for this energy.

There are also two small changes to the text, where we cite other fluid vorticities:

Line 307: Rather than report the vorticity of a "typical" toranado (10^{-4}), we now tell the cores of supercell tornados (10^{-1}).

Lines 310-11: New reference to superfluid nanodroplets (10^7 !!!) recently published in Science.

Also, the STAR author list (as of 11 Nov 2016) and acknowledgments have been included.




------------------------------------------------------------------------------------

This paper was at an advanced stage in the GPC process as a PRL manuscript, when at the OSU meeting the decision was made to rewrite the thing for submission to Nature.  This was rather a frustrating development, but at the end of the day, I think the result was something we can be quite happy about.  On 6 October, the PAs submitted "Nature v2" to the GPC.  It is in the attached file list at the bottom, or it can be accessed directly here https://drupal.star.bnl.gov/STAR/system/files/LambdaPolarizationNature_v2.pdf

GPC members as well as some other STAR members have provided feedback on this manuscript.  This feedback, as well as PA responses to it, are listed below.  This has resulted in a slightly revised manuscript we are calling "Nature v3a."  It is in the attached file list at the bottom, or it can be accessed directly here https://drupal.star.bnl.gov/STAR/system/files/LambdaPolarizationNature_v3a.pdf

After sending around the previous version, Declan sent a list of comments/suggestions (which he may have sent before and I lost!).  I have also addressed these, leading to version "Nature 3b".  It is in the attached file list at the bottom, or it can be accessed directly here https://drupal.star.bnl.gov/STAR/system/files/LambdaPolarizationNature_v3b.pdf


From Bill Llope
From Aihong Tang
From Declan Keane
From Evan Finch
From Art Poskanzer
From Rosi Reed

---------------------------------------------------------------------
Issues to discuss at our GPC meeting on 14 Oct.

• Both Evan and Rosi raise the point that rapidity (and "midrapidity") may need to be defined in a Nature article.  This is not 100% obvious to me, but I could imagine this.  I have not come up with a smooth, natural way to do this.  Everything I have tried has been awkward.  Delcan made a suggestion to say that midrapidity particles are those with small velocity component in the beam direction.  Perhaps that is enough?  Evan suggested a footnote.  Other suggestions?
• What is "the best" reference for when we first mention the QGP?
• How best to describe the "systematic uncertainty in scale" for vorticity?  (See around line 164.)
• And most important of all.... any fun suggestions for a sexier title?

---------------------------------------------------------------------


Bill Llope:

There appears to be a stranded sentence fragment on lines 93-94.
And i think you might remove the "come on it is!" on line 200 although it is humorous

Response:  Oops, yes sorry.  This came at the last second as either Sergei or Mike hit carriage return in a commented-out line.  Fixed.

Bill's further comments sent 17 October 2016:

it reads nicely. here are some small things i noticed.
(note this is the first time i read it carefully for the english)

Thanks for your careful reading.

...I'm struggling with capitalization rules...
i think strong force on line 33 should not be capitalized. here it
is being used as common not proper nouns...
on line 65, Time Projection Chamber was capitalized. This
is o.k. as it is the name of that specific thing - hence
a proper noun. Same for the capitalized relativistic heavy-ion collider
on lines 36-37 - perfectly o.k.
You correctly do not capitalize quantum
chromodynamics on line 59... But you do capitalize it on
lines 12-13. This is making my head swim, but i am thinking
that quantum chromodynamics on lines 12-13 should not
be capitalized just like strong force on line 33 should not.

Response: I agree that quantum chromodynamics should not be capitalized on line 11, so have changed that.  However, I disagree with your suggestion regarding Strong Force.  It is a "specific thing" just as TPC is.  It is not just a strong force.  It is the Strong Force.  You are not the first one to make this suggestion, however, and I will relent if too many people object.  I do think it should be capitalized, however, and am going to try to at least submit it to Nature as capitalized.  Let's let them decide.

line 25 - i think you need "the" before both Lambda symbols.
I don't like using variables as words in general as done on this
line and prefer instead constructions like on line 21.

Response:  I could put "the $\Lambda$" but (1) it still "uses a symbol as a word" and (2) it actually reads even worse.  We cannot write "Lambda."  But I can see your preference for "$\Lambda$ hyperons" as on line 21.  So I'll change it to that.

line 56 - change "the" to "this"

Done.

line 63 - we got more than a billion in run-14 Au+Au alone.
"tens of billions"?

I will change it to "billions."

line 75 - "allows THE experimental"

Response: I disagree.  It's like "payment of the fee allows access to the museum."  One *could* say "payment of the fee allows THE access to the museum." but it doesn't sound as good and does not convey more information.

missing space after closing paren and before hyphen on line 82

Fixed, thanks.

line 96 "In addition to more fully characterizing" is awkward.
You could, without any loss of content just axe the
phrase "In addition to more fully characterizing the unique fluid cre-
ated in these collisions," and just join the rest with
the previous paragraph

Yes, very good.  Thanks for that.

line 114 - why semicolon construction there. Just use a period.
OTOH, i think the semicolon construction on line 140 is fine
as is.

Okay.

line 125-126 - in our field, we WAY overuse the words "limited
statistics" when we really mean "limited event sample sizes" and/or
"limited statistical certainty". In a Nature paper, we should
try to use plain and easy to understand language.

Dude.  "Limited statistical certainty?"  That's a thing?  Googling the term "statistical certainty" gives *some* examples, but it's not common....

Okay, well it's not only *event* sample sizes, but also *hyperon* sample sizes.  So, I'll replace "The limited statistics of our datasets" with "Our limited sample sizes," how's that?

135 replace "momentum" with "momenta"

Okay. (Though I like it momentum.)

145 and 147  "times THE statistical"

Okay thanks.

148 remove hyphen

Okay done.

152 replace "fall" with "decrease"

Okay, good.

152 replace colon with period and capitalize "It"

Okay. (Though I prefer the semicolon.  I admit that I do like semicolons perhaps a bit much...)

155 replace comma with "and"

Okay, good.  That does make it clearer.

158 replace "hydrodynamics " with "a hydrodynamic- "
(notice the hyphen after)

Yes, good, thanks.

This sentence is also pretty long. I think you can break it
by replacing "[21], in which the fluid" to  "[21]. Here, the fluid"

Thanks for the suggestion, but I would prefer to leave it long.

166 change "accounted for" to "estimated" and
change "and produce" to "and they produce"

Okay.

182 replace "According to the" with "According to an"

Okay.

189 remove "actually"

Okay.

195 here i make the same comment as before
"increased event sample sizes"

Okay.

200 missing spaces before both dashes

Okay.


202 not sure about this one but i am thinking
"field" should be plural

Yeah, it's kind of fuzzy, but I would agree with you.  I'm making it plural.

201-205 kind of too long. break after "system"?

It is long, but I would rather not break it, as it is more or less a summary of the significance of the results.






Aihong Tang:

This draft reads very well to me. I really like the idea of collecting vorticity at different scales and compare with !

Response:  Okay there isn't really any response required here, but it's nice to hear that others like these comparisons, too.



Declan Keane:

Please consider citing this paper:  Laszlo & Horst, J. Phys. G Nucl. Part. Phys. 41, 124001 (2014).

Response:  Yes I (Mike) have this one in my large collection of hydro-vorticity-related papers.  I'm not a giant fan of this paper (too self-referential and selective for a paper whose title suggests a more general review), but I can see how it can be appropriate.  Please take a look at where I have included it (toward the end of paragraph 2), and see whether this makes sense. 

We are only allowed a maximum of 30 references, so if we find several references that we think we really need to cite, this Csernai/Stoeker one might be in peril, but I don't mind it otherwise.


Additional comments from Declan, on version 3a:

Fig. 2: In the inset, the ‘6’ at the end of the horizontal axis is cut off.

Yes, thanks, fixed.

Fig. 2: I mentioned before about the aesthetics of making the inset have a black background, and I assume you don’t like that idea.  I’m fine with that, but I’m still interested to see your answer.

You did mention that, and I forgot entirely.  I have made it black.

Fig. 3: This is a picky point, but the red arrow that goes with the spectator matter on the left side doesn’t look like it matches the red arrow on the right, and is hardly even recognizable as an arrow. If you tweak its position, it should look more recognizable.

They do match!  Actually, it seems I am often changing viewing persepctive etc, to achieve the perfect effect.  Let me collect further feedback of this kind on this figure, so I can address them all at once.  It is nontrivial and a lot to balance.

Line 22: “…hydro predictions with extreme vorticity.”  Non-experts might think you mean that vorticity in hydro can be ramped up or down, and you are talking about where it is ramped up to an extreme case. One possible solution is to just remove the last three words.

Well... it is a good point.  I mean, it is ROUGHLY consistent with SOME hydrodynamic predictions....  In v3b, I replace "consistent with hydro predictions with extreme vorticity" with "consistent with some hydro predictions."

Line 28: “…resulted in a null effect.” Rephrase to something like “…did not observe a signal.”

Right.  Good.  Done.


Line 29: Non-experts might be puzzled by “perfect fluid” coming out of the blue here.  A simple fix is to just cite [10].  Lower down, on lines 50-51, it is explained nicely.

Great, thanks.  Done.  Please take a look at the new formulation, where I also put quotes around perfect fluid in the summary paragraph.

Line 32: Does ‘strong force’ need to be capitalized?

Well, I think so.  Otherwise it is just a strong force, like from a stiff spring.  Of course, you could say the article "the" already distinguishes it (kind of like "The" Ohio State University...), but the strong force from a stiff spring also can have "the" in front of it, as it did earlier in this sentence.  :-)  I'm sure Nature has a policy on this, and will capitalize/uncapitalize as they wish.  I would like to leave it until they do.

Line 45: Why pick [9] as the canonical paper to define QGP?

You know, it's slightly arbitrary.  I am very happy if people would like to choose another one.  The thing is, Shuryak (I think, right?) did coin the phrase quark-gluon plasma.  But he did it in these obscure articles that are just crap to read.  I guess I kind of wanted to give him his due.  But I am open to any other suggestion.  (Made boldface to remind us to follow up.)

Fig. 1 caption: I’m agnostic on whether it’s essential to explain midrapidity, but no harm to do it if you find a smooth way. Here’s a suggestion: “…emitted at midrapidity” -->  “…emitted at midrapidity (i.e., having a relatively small component of velocity along the beam direction)”

I like this.  Let us try it.

Line 68: Some readers might be confused here, but you can avoid the problem by “…fragments from the collisions that experience…” --> “…fragments that experience…”.  

Ah, get rid of the (superfluous) "from the collisions".  Good.

Line 71/72: “mid-central” is definitely jargon. What about “typical”?

Okay.  That seems good.

Fig. 2 caption: I didn’t see an answer about my earlier suggestion to explain that the horrible rat’s nest of tracks here is just an artifact of the projection of 3D tracks onto a single plane. I suggest the same explanation as the last Nature paper. A lot of intro physics textbooks and TV shows about science show bubble chamber images where the raw data is only a 2D projection, so this idea is very widely held.  It’s important to clarify this point.

Declan, I seem to have lost all of your earlier suggestions!  Did you send them to me?  But yes, I do recall you telling them to me in the hall in Seattle.  I agree that is is important.  I have added the sentence "The tracks are reconstructed in three dimensions, making them relatively easy to distinguish, but are projected onto a single plane in this figure."

Fig. 2 caption, 3rd line from end: “and hyperons” --> “and the parent hyperons”

Yes, definitely.

Fig. 3 caption, 3rd line from end: “the fluid the beam” --> “the fluid and the beam”

Damn.  That was an error INTRODUCED in v3b.  Fixed.  Thanks.

Line 114:  ;” à “;

I see your point, but my religion prevents me from implementing your suggestion.  That is to say, the nuns in my Catholic school made it the Eleventh Commandment to enclose commas, periods, and semicolons in the quotation marks.  I do believe they are correct.  Let the nuns at Nature decide.

Lines 139-141:  Why is this important sentence in parentheses?

I dunno.  Maybe perversely, it is actually to emphasize the point, rather than deemphasize.  I can see it either way.  I am going to leave the parentheses, but let us see on the phone meeting what people say.  (Made boldface to remind us to discuss it.)

Line 146: “not entirely clear” --> “not clear”

Good.  Done.

Line 161: What methods section?  Is it coming later?

Yes, it is.  Nature goes to some pains to emphasize that the Methods section should NOT repeat documentation of standard procedures.  So, no long descriptions of centrality selection or reactionplane determination or Lambda topological cuts etc.  Only stuff special to this analysis that wouldn't be found elsewhere.

Until now, we had decided such a section would not be needed for this paper, but now we want to have a short, ~4-paragraph prosaic section on just a couple of details.   We are going to list the feed-down fractions from THERMUS that provide the effect of feed-down on the vorticity and magnetic field.  We will also put something about the off-peak fluctuations that give systematic errors appearing in figure 4.  The whole thing will be half a page or less.  It is in bullet form at the moment.  It will be completed by beginning of next week.  I hope we can converge on the physics paper itself even while I put together these paragraphs.

Line 164: Do you mean that the sys error is + 8 and -4?  Can you re-phrase to make it clearer?

I am finding it stunningly difficult to state it clearly (and even worse to plot!).  Here is the thing: Changing the feed-down and/or changing the assumed freezeout temperature (especially this latter one) changes the SCALE.  So, if the vorticity is [8+/-2] (2 being the statistical uncertainty), then when I say that we have a "systematic uncertainty of a factor of two" that means our answer can be [4+/-1] or it can be [16+/-4].  In other words, we want to make it very clear that the statistical errorbar scales the same as the central value.  I would love suggestions of the most natural way to say this.  (Also, how to plot it, when the time comes?)  I won't make changes now, hoping that someone has a good suggestion.

Line 185: Don’t start a new paragraph here. If you think this paragraph would be too long, a better place to break would be line 178.  But I don’t think a break at line 178 is needed.

Agreed.  I have made it all just one paragraph.

Line 189: “the hope is…”.  This wording is too timid about what BES-II will do.  I’d say “the expectation is…”

Good.  Done.

Line 197: journals don’t allow conversational contractions.

Right.  Plus, it was a bit colloquial.  I got rid of "than we've had before."

All references:  Phys. Rev. doesn’t allow arXiv references if the paper is already published in a journal.  I expect Nature has the same rule.  I guess it’s convenient to leave them there while the paper is under review within STAR, but remind people when you post on STARpapers that the arXiv references will be removed before submission.

Okay.  Yes, Nature clearly has a different style (e.g. the article titles are listed in the bibliography).  If they would take bloody .tex files, then they could just provide a .bst file and everything would be fine.  But...  we'll do whatever they say, at the end.

Line 218: St\”ocker

Right, thanks.


P.P.S.  I just noticed that the title hasn’t changed since the PRL version.  That’s OK, but at least we should kick around the idea of a sexier title.  Maybe something with vorticity.

Actually, yes.  We need a better title.




Evan Finch:

Here are my comments.  The draft reads really well, so I’m mostly down to noting very minor grammar comments.

One slightly larger comment: Page 3: Line 165 “The data..” should I think start a new paragraph, as these next few lines justify the main point from the summary paragraph.  I’d really then like to see at least one or two more sentences summarizing from your methods paper how this number for vorticity is arrived at, even a very vague description.  It feels like this paragraph is a big one for the paper and could stand to be stronger.

Response:  This is a good point.  We've split the paragraph as you suggest, to emphasize the main physics point.  In terms of summarizing the methods paper, we will put this into the Methods section.  That way, we can also include the *numbers* that go into the accounting for feed-down effects.  Isaac is working on the Methods section, and this is almost the only thing we plan to put in there.  (Nature goes to some pains to say that they do not want "standard" procedures elaborated upon, unless they are crucial.  While this is a little vague, we don't, for this reason, plan to include the reaction-plane-resolution correction.)


Small comments/suggestions/questions
page 1:
line 58.  “Nature"  capitalized?

Response: yeah, that does look a bit "dramatic," doesn't it?  It is now lowercase.

line 66: Does “midrapidity” need explanation for Nature?

Response: Actually, this I do not know and I had been wondering how/whether to do it..  Looking at other articles in Nature in other fields, I see reference to variables that I am not familar with, as an outsider.  Looking at the STAR articles in Nature, I see that the pbar-pbar paper did not use rapidity, and that pseudo-rapidity was mentioned in the 4He paper, explicitly explaining it in more familiar terms.

In v2, "rapidity" is mentioned 4 times (3 of those being "midrapidity").  Looking again, I decide that its usage at line 87 is superfluous, so that is gone.

The other uses of the word are at lines 66, 150 and 151. 

I would very much welcome GPC suggestions on the best way to handle this.

line 69: remove comma

done

line 72: "mid-central” may be too jargon-y for Nature.  If so, you could point to Figure 3 as an illustration.

Response: Actually I think this term is one that translates well into colloquial use.  Since the paragraph begins with reference to "head-on" collisions, I feel the reader will correctly understand what "mid-central" means.  We could use something like "somewhat off-center" or even get into "impact parameter," but I don't see the need and prefer "mid-central" to these.

line 75: I’d remove “(within some resolution, which can be …)” since you make this point below equation 2.

Response: Yes, this is a good idea.  I am going to keep it commented out in the .tex file, since I won't be shocked if I get the opposite comment from another collaborator ;-)

Fig 1 caption:  99.995% could be replaced by “nearly” (since you give a range of velocities in the text.)

Response:  Very good, yes.

page 2:
Figure 2 caption: perhaps mention strength of B-field since you compare to it.

Response: Good.  Done.

Figure 2 caption: at end, say that the invariant mass distribution is shown as the inset.

Response: Thanks, done.

line 93-94: editing error

Response: Thanks

line 122: you can get rid of one of the “=0.642”

Response: yes, thanks.

line 126: In this paragraph, it may make sense to switch 2nd and 3rd sentences.

Response: I can see how it could work that way, but I think it works better the way it is written.  Please let me know if you feel strongly, and we can discuss.  I know how an author can have trouble seeing anything but his own logic.

page 3: line 192: Why not be more exact than 2sigma?  You quoted the Average Polarization as 7.2 sigma.

Response:  Yes, this was conscious.  Let me explain.  I don't see the point to be more exact here.  Indeed, I would feel a bit silly to do so.  As for the 7.2 sigma (and 4.2 sigma for AntiLambda) mentioned earlier, that is very important.  The statistical significance of our results (i.e. is there even a significant signal at *ALL* for STAR to discuss?) has been brought up twice by at least one prominent and vocal member of the field.  I believe it is very important to leave zero doubt on this front, otherwise the rest of the analysis/discussion is built on sand.  Therefore, if I were asked to state the 7.2 and 4.2 numbers with *less* precision, I would insist on saying "more than 7" and "more than 4."  Indeed, I would not mind doing that, but then I fear that I'll be accused of misleading the reader; i.e. the complaint will be that "come on, it's only a LITTLE more than 7 (or 4)."  So, I feel most comfortable just letting the numbers speak for themselves.  It makes much less sense to do that for the "2sigma" effect later on.


Evan's further comments made 17 Oct 2016:

Looks really good. I’m down to three grammar suggestions, the last two of which you can take or leave as you wish:
—line 13, “restoration…are” should be “restoration…is”

Good catch.  Thanks.

—line106 “measuring the polarization…can be used to measure B...” is an odd construction.   How about “polarization measurements…can be used to determine B...

Yes, totally agree.

—line 124, How about “However, when averaged over all phase space, symmetry demands that …”  ?

Okay.




Art Poskanzer:

Very nice paper, and the way it is written, it is appropriate for nature.  I am sure your GPC will have the comments I can make, but to be sure here they are:

Does it say that the “heavy ion” is “Au”?

Response: This is mentioned in line 64 and in the caption to figure 1.

6: “vortical" should be defined the first time it is used, not on 83. Maybe the “swirl” should be move up here but the equation left where it is.

Response:  I see the general point to define terms, but the "vorticity of a fluid" is something that I believe is sufficiently meaningful to most scientists, and defining it in the abstract (summary paragraph) would be distracting.

Indeed, I refer you to the "example summary paragraph" from Nature, where you will see many terms that have literally no immediate meaning to the non-expert reader.  "Vorticity" of a fluid is much more colloquial than those terms.
https://drupal.star.bnl.gov/STAR/system/files/NatureGuidelinesSummaryParagraph-1.pdf

7: “evolve in the presence of” -> “produce”. Otherwise it sounds like an external field

Response:  Well, this is actually an interesting point, as the fluid *might* indeed produce some of the field itself.  However, as a matter of fact, we (the field in general, consider CME etc) mostly do consider the B-field to be "external" to the fluid, produced by the spectators.

Having looked at that sentence again, however, I changed "evolve" to "evolves."

20: the first time you mention Lambda you should say “self-analyzing for polarization"

Response: If I understand you correctly, I disagree.  They have a positive polarization.  The *way we determine that* is by exploiting their self-analyzing nature.  But it is not a "self-analyzing polarization."

But perhaps I misunderstand your suggestion.  If so, maybe you could explain it in a different way?

All, or none, of the figure caption should say “(Color online)”

Response: For a Nature article, there should be no "color online" statements.  We had one in Figure 4, a holdover from when this was a PRL draft.  Thanks, it is removed.

63-7: “fig.” or “figure”

Response: Yes, we have to be consistent here, and we were not.  Looking at other Nature articles, I see that "figure" is written out fully.  "Fig." is just used in parentheticals like "(Fig. 1)".  I changed our one "fig" to "figure."

108: Is “B” defined?

Response: No, it was not.  I have now put in the definition earlier in the sentence.  I suppose you are right that we had to do that, but it does make the sentence a bit more awkward.

12: Do you need a second “0.642”?

Response:  Thanks.  It is removed.

200: take out the hyphens and say “related to”

Response:  Yes, that's a good idea, thanks.



Rosi Reed:

I really like it, it's extremely well written and a joy to read.  :-)
I have  a few comments below (yeah, I'm unable to just read a paper
... sorry....).  But this is really great.


10: They are also of particular interest currently, -> Currently they
are also of particular interest,

Response:  Your suggestion is a good one, but now that I take another look at that sentence and construction, I have decided to remove the word "currently" altogether.

32: the theory of the Strong Force. -> Seems a little weird to call it
the strong force after calling it qcd a few times.

Response:  Well, I do this on purpose.

(1) This is in the part of the summary paragraph where we are supposed to "bring this back to a larger context," and bring the general reader back in.  The Strong Force is slightly more colloquial.

(2) It's nice to mix things up and not repeat the same terms.

(3) Here is the main reason: The Strong Force and QCD are different things.  The Strong Force is a phenomenon, and QCD is a theory.  (We believe QCD is the correct theory of the Strong Force, but that doesn't mean that they are the same.)  That's why, above, I talk about "symmetries of QCD" rather than "symmetries of the Strong Force."  Theories have symmetries.  You may say it is quibbling, but I feel rather strongly that the difference between the phenomenon itself and our theory of the phenomenon is a valid one.

(That said, I recognize that I am not being pure.  The final sentence should/could probably read "... insight about the Strong Force" rather than "insight about QCD."  I would personally prefer that, but I suspect co-authors would complain.  If they complain about its use in the abstract, however, I am going to stand "Strong.")


35: Would the spin people object to hi collisions being the primary objective?  Perhaps this could be softened for diplomacy….

Response:  I don't guess they should object to "heavy ion collisions" being the primary objective of the "Relativistic Heavy Ion Collider" :-)


52: large teams have undertaken a program of experimental investigation, -> sort of a meaningless set of words, which distracts from the point about hydrodynamic theory

Response:  It would be rather strange in a regular article (e.g. in PRC), but these are the sort of terms ("large teams", "program of investigation") I find in other Nature articles, to try to give a sense of the "sweep" of the field.

58: You’ve used Quantum Chromodynamics already a couple times, so maybe you should put the QCD acronym the first time you use it.

Response: That term is only used twice.  Once is in the "summary paragraph" (something akin to an abstract) and then again in the place you refer to.  I don't like to define an acronym in the abstract and then "use" it later.  Basically, the abstract and the rest of the text are usually considered two separate documents from this point of view.  After this point, the acronym is used exclusively.

63: you use fig. 1 here, but figure 2 or 3 later….

Response:  Yes, thanks.  Nature uses the full "figure," so I have changed our usage to that form.

66: I’ve never written a nature paper, but it seems to me that midrapidity is not a generally known word….

This is the same comment a Evan's and again I would very much welcome GPC suggestions on the best way to handle this.


Fig 2 caption: Probably should mention that the invariant mass is the insert.

Response:  Yes, thanks.  It is done now.


113: measure the spin direction -> measure the direction of spin

Response: I prefer to avoid "... of ... of ...".  Otherwise, I would agree with you.

137: denote an average over hyperon momentum and over events. -> denote an average over hyperon momentum and events.

Response:  Okay, thanks.


150: A less vortical source at midrapidity?  Why would this happen?  I
see why there can be a T dependence to the vorticity, and of course
the total angular momentum would depend on sqrt(snn) for a given
impact parameter, but outside of these what other mechanisms could
decrease the vorticity at a higher sqrt(s)? [ok, it’s late so I’m not
going to read reference 18 which probably explains this tonight,
though I’ve saved it to my laptop for later]

Response:  Yes, read reference [18].  But others have also suggested this, in fact, including some Russians (I think the "vortical tornado" guys) and Csernai


165: 18 orders of magnitude?!?!?!!!  Holy shit.

Response:  I will take this as a comment.


189: The facts that PΛ is consistently larger than PΛ and that the
energy-averaged difference differs from zero by 2σ, -> Since PΛ is
consistently larger than PΛ and the energy-averaged difference differs
from zero by 2σ, the hope is that

Response:  Yes, very good, thanks.  I had also found my formulation somewhat awkward but could not think of a better way.






--------------------------------------------------------------------------

---

Analysis Note: https://drupal.star.bnl.gov/STAR/blog/iupsal/lambda-polarization-cumulant-method-analysis-note

• Additional documentation on feed-down effects on the polarization, and systematic uncertainty estimate: https://drupal.star.bnl.gov/STAR/system/files/GeneralCase.pdf

Paper proposal: https://drupal.star.bnl.gov/STAR/lambda-polarization-prc-paper-proposal