Dear Brahms'ers, I have just received the enclosed referee's report on the 200 AgeV ratios paper. While I have not digested the details I find the report quite positive and constructive. In fact, the referees give us more leeway to discuss the physics issues, than we have allowed ourselves! I will go through the comments in detail and come up with a suggestion for rewording and response letter. cheers JJ PS: While this goes on, we should not forget the other good data and should move towards publication of a stopping letter and a yields/strangeness letter. There is no reason to wait considering that we will not run Au+Au in run III. ____________________________________________________________ Jens Jørgen Gaardhøje, Assoc. Prof., Dr. Sc. Niels Bohr Institute, Blegdamsvej 17, 2100 Copenhagen, Denmark. Tlf: (+45) 35 32 53 09, secr. (+45) 35 32 52 09, Fax: (+45) 35 32 50 16. UNESCO Natl. Comm., secr. (+45) 33 92 52 16. Email: gardhoje@nbi.dk. ____________________________________________________________ ----- Original Message ----- From: "Physical Review Letters" <prl@ridge.aps.org> To: <gardhoje@nbi.dk> Sent: Tuesday, September 10, 2002 11:55 PM Subject: Your_manuscript LU8319 BEARDEN > Re: LU8319 > Rapidity dependence of charged antiparticle-to-particle ratios in > Au+Au collisions at $sqrt s N N = 200$ GeV > by I.G. Bearden, D. Beavis, C. Besliu, Y. Blyakhman, et al. > > Dr. J.J. Gaardhoje > Niels Bohr Institute > Blegdamsvej 17 > DK-2100 Copenhagen, DENMARK > > > Dear Dr. Gaardhoje: > > The above manuscript has been reviewed by our referees. We ask you > to consider the enclosed comments from the reports. > > While we cannot make a definite commitment, the probable course of > action if you choose to resubmit is indicated below. > > ( ) Acceptance, if the editors can judge that all or most of the > criticism has been met. > > (X) Return to the previous referee A for review if available. > > ( ) Submittal to new referee(s) for review. > > Please accompany any resubmittal by a summary of the changes made, and > a brief response to all recommendations and criticisms. > > Yours sincerely, > > Jerome Malenfant > Senior Assistant Editor > Physical Review Letters > Email: prl@aps.org > Fax: 631-591-4141 > http://prl.aps.org/ > > > -------------------------------------------------------------------------- -- > Report of Referee A -- LU8319/Bearden > -------------------------------------------------------------------------- -- > > Whether this is suitable for PRL is a tough call. On the one (negative) > hand, the y=0 measurements are confirmations of earlier measurements by > PHOBOS (nucl-ex/0206012), submitted to PRC a month earlier. Also, the > rapidity dependence for p-bar/p was already established at 130 GeV in a > PRL, and an abrupt change wasn't really expected when moving to 200 GeV. > The trends of all p_t, centrality, and rapidity dependences are expected. > > On the other (positive) hand, the high-quality, finely-binned rapidity > dependence for p-bar/p and K-/K+ (Fig. 3) presented in this paper offers a > formidable challenge to modelists investigating things away from > midrapidity (this should be pointed out by you!). And the empirical > relationship between mu_S and mu_B (Fig. 4), based on experiment, is a > nice and concise result. Both of these figures were widely admired and > discussed at Quark Matter 2002 conference two weeks ago, and provide the > paper with a solid foundation. > > However, in its current form, the paper is being stretched too thin. For > example, the 3rd and 4th paragraphs are redundant and should be removed, > since the combination is a near-exact copy of the discussion on Figure 3 > later in the text (paragraph beginning with "Figure 3 shows..."). Also, > the observations of midrapidity boost-invariance and low net-baryon > density (low mu_B) are stated several times in the paper. Even the > detector discussion is probably more detailed than it needs to be. > > Therefore, I think that the paper in its current form needs more substance > to warrant acceptance in PRL. In my opinion, some substance can be added > near the end of the paper in the discussion on chemical potentials and the > relationship between the ratios, which I'll explain here. > > The paragraph which starts with "Surprisingly..." needs the most revising. > First, the "surprisingly" isn't really necessary; a monotonic relationship > between mu_B and mu_S is expected from statistical models employing both > baryon number and strangeness conservation (in fact you point this out > yourself in the paragraph's 6th sentence). The fact that K-/K+ is not > equal to 1 at these energies is due entirely to the non-zero mu_B. > > Put another way, even if many/most hadrons are produced as > antiparticle-particle pairs, *any* stopping in the collision means that > the p_bar/p ratio must be less than 1 or baryon number is not conserved. > Then, since mu_b is nonzero, the existence of the other conservation laws > (strangeness, charmness, isospin) leads directly to other finite chemical > potentials and non-unity ratios. > > For example, a finite mu_B must lead to non-unity anti-Lambda/Lambda > (etc.), which needs a non-unity K-/K+ to balance the resulting net > strangeness (strangeness is still conserved even though mu_S is nonzero). > Of course this is very simplified, but the point is that it's not a > surprise that mu_s and mu_q are related. They *have* to be. See papers by > Redlich, Becattini, Magestro, Rafelski, etc. > > I write all of this because I think the discussion in the pre-summary > paragraph can be developed much further: > > * Why is 1/3 the expected value (not straightforward to everyone)? > * Why might your result fit to a power law with exponent = 1/4 instead of > the expected 1/3? > * What role do strange baryons play in the relationship between proton and > kaon ratios (hint hint)? > * Is there a quark-counting reference or scenario which can be developed > here? > > I understand that this is an experimental paper and you may not have > wanted to use lots of space on this type of discussion, but it is useful > to explain the result and to conjecture about the source of the 1/4 in > Fig. 4. It would also be helpful to elaborate on what it means to assign > mu_B to points away from midrapidity... is the system in chemical > equilibrium at these places? > > Either way, I feel the paper in its current form needs revision and > extension in order to be accepted as a Letter. I hope my comments are > helpful to improving the content of the paper. > > Other points needing attention: > ------------------------------ > > The introductory paragraph summarizes qualitatively 1/2 the results of the > paper... a more general introductory paragraph would be better, saving the > discussion of rapidity trends for a new paragraph with more development. > > Paragraphs 3 & 4 should be removed (explained above). > > In paragraph beginning "The data presented here...", are we to assume that > the same number of events was recorded for the two magnetic field > directions for each spectrometer configuration? In PHOBOS' recent paper > there is a discussion of weighted averages when determining ratios based > on changing field orientation that seems just as relevant here. > > The feeddown discussion (paragraph begins with "The ratios shown in Fig. > 2...") is incomplete. In addition to STAR, PHENIX has measured /\'s > systematically but is not cited. Also, the STAR paper referenced there > does not contain lambda/proton~0.5... where does this come from? > > You give initials for Grand Canonical Ensemble (GCE) but never refer to it > again. > > Figure 2's caption contains "antihadron/hadron" and Figure 3 contains > "Antiparticle-to-particle"... please choose one and stick to it. > > In the summary paragraph, just call them charged kaons, not "charged > singly-strange mesons". > > > -------------------------------------------------------------------------- -- > Report of Referee B -- LU8319/Bearden > -------------------------------------------------------------------------- -- > > It is the opinion of the referee that the results on > particle/anti-particle ratios obtained in Au-Au collisions at 200 A/GeV > are of general interest as they provide more complete understanding of the > dynamics of particle production in ultrarelativistic heavy ion collisions. > In addition the scaling between K^+/K^- and \bar p/p ratios presented in > this paper is very interesting. Thus, I consider that the paper contains a > sufficient amount of new results that can be published in Phys. Rev. Lett. > However, before publication I would suggest to make the following minor > corrections: > > 1. The authors should define \mu_s as the strange-quark chemical potential > 2. After the sentence on p 8 "..a value of 1/3." I would recommend > to give a reference to P. Koch et al. Phys. Rep. 142 (1986) 167 and to > J.Cleymans et al. Z. Phys. C57 (1993) 135. > 3. The authors should indicate that the relation \mu_s=1/4x\mu_q > is only approximate and is valid only if neglecting contributions > of strange and multistrange baryonic resonances to K^+, p and their > antiparticles. > > After the above changes have been made I would recommend publication of > the above manuscript without further contact with this referee. >
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