[Brahms-l] K/pi article submission

            Dear Brahms,

        I just received the answer from PLB following the submission of
the K/pi paper.
The referee reports are quite positive (see below) and only minor
improvements are suggested. Right now i am still at home for vacation but
i will make the necessary modifications in about one week (i return to GSI
on sunday) and send you the new version.
        Thank you very much for all your help.

                     Best regards,
                            Ionut



---------------------------- Original Message ----------------------------
Subject: Your Submission
From:    "Volker Metag" <PLB_at_exp2.physik.uni-giessen.de>
Date:    Tue, January 5, 2010 10:01
To:      i.c.arsene_at_fys.uio.no
Cc:      PLB_at_exp2.physik.uni-giessen.de
--------------------------------------------------------------------------

Ms. Ref. No.:  PLB-D-09-01469
Title: Kaon and Pion Production in Central Au+Au Collisions at
\sqrt{s_{NN}}=62.4 GeV
Physics Letters B

Dear Dr. Ionut Cristian Arsene,

Reviewers' comments on your work have now been received. Both reports are
very positive. Minor improvements are suggested. Would you please submit a
revised version of the manuscxript as soon as possible.

For your guidance, reviewers' comments are available to you from the EES
website. For your convenience reviews sent to us in plain text format are
also appended below.

If you decide to revise the work, please submit a list of changes and a
rebuttal against each point which is being raised when you submit the
revised manuscript.

To submit a revision, please go to http://ees.elsevier.com/plb/ and login
as an Author.
Your username is: ionut.arsene
If you can't remember your password please click the "send password" link
on the login page.
On your Main Menu page is a folder entitled "Submissions Needing
Revision". You will find your submission record there.

Yours sincerely,

Volker Metag
Editor
Physics Letters B

Reviewers' comments:


Reviewer #1: The manuscript "Kaon and pion production in central Au+Au
collisions at sqrt(s_NN) = 62.4 GeV" by I.C. Arsene et al. (BRAHMS
Collaboration) presents invariant differential transverse momentum
distributions of charged pions and kaons from central Au+Au collisions at
an available energy of 62.4 GeV. By integration of the spectra rapidity
densities of the charged pions and kaons are deduced as function of
rapidity over a wide rapidity range. Meson yield ratios are shown as
function of rapidity and as function of the antiproton to proton ratio,
which is closely related to the baryon chemical potential. A comparison
with data from measurements in the lower AGS and SPS energy ranges
indicates a universal dependence of the charged meson ratios as function
of the antiproton to proton ratio. This observation is interpreted in
terms of local fireball formation at different rapidities along a
universal freeze-out curve in the temperate - baryon chemical potential
plane. A
comparison with transport models indicates some qualitative description of
the trends observed in the data but a quantitative agreement is lacking.

The manuscript is written well, the analysis seems to be sound, and the
results are interesting for a wider audience. Therefore, I recommend this
manuscript to be published in Physics Letters B.

Nevertheless, I have a few minor comments and suggestions which I list in
the following for the consideration of the authors for a revised version
of the manuscript. The comments are given according to the line numbers in
the manuscript (thanks for providing these):

- 51 - 52: replace "extends well towards" with "comes close to".

- 57 - 58: replace "comparable production of anti-hadron and hadrons" with
"the yields of produced anti-hadrons and hadrons are similar".

- 74     : add "polar" before "angular coverage".

- 78 - 81: split this into two sentences, e.g.: "Particle identification
(PID) is achieved in both spectrometers using time-of-flight walls   (TOFW
in MRS and H2 in FS). In the FS a ring imaging Cherenkov detector (RICH)
is used in addition."

- Fig. 1: concerning the scaling factor 0.2^n, please indicate which value
of n was used for which rapidity.

- 119: replace "in" with "from".

- 186: the yields of pions and kaons were not extracted in the same
rapidity intervals, which has to be corrected for. What the reason for
this inconvenient choice of rapidity intervals?

- 196: replace "somewhat more pronounced" by a quantitative statement.

- Figs. 5 & 6: the theory curves are hard to distinguish from each other
in black & white print, but that's probably difficult to improve.

- 225 - 226: while you state that UrQMD does not reproduce the observed
dependence of the K-/K+ ratio on pbar/p, I'd say that the qualitative
trend is described reasonably well. At least, the qualitative agreement
between the trends observed in data vs. model is as good as it is the case
for the K/pi as function of pbar/p, which you claim not to be bad (lines
245-248). The model comparison is not the main point of this manuscript
but I'd suggest to apply similar criteria concerning what can be accepted
as a qualitative description of the trend observed in the data.

- 254 - 256: when the three sets kaon spectra in the rapidity interval 0 <
y < 1 are fit simultaneously, giving just a single value for T_eff, only
this one data point should be plotted in Fig. 7 instead of the three data
points that are shown at the moment.

- 306 - 313: see 225-226.




Reviewer #2: This is a very well written data-driven paper
which has only a few flaws that I'd like to
comment on. The paper should definitely be published
by PLB after my comments have been incorporated.
Since these are minor additions and modifications
to the text I don't have to review the paper again
as long as the points have been taken into account.

The technical part (experimental details, data
analysis, error description) is very well worked
out and contains the right amount of detail.

My only comments relate to the introduction, the fits
and the data interpretation.

First, the introduction:
I think it is presumptuous to equate the K+/pi+ structure
at SPS energies to a QGP transition (lines 21-27, and then
further on up to line 40 in the text). Clearly this
phenomenon is related to a switch from a baryon dominated
phase to a meson dominated phase, which per se does not
require a phase transition to quarks and gluons. Furthermore
the exact shape of the 'horn' has been recently well
reproduced by hadronic models which simply include higher
hadronic resonant states (Hagedorn states) without a transition
(see the Andronic, PBM, Stachel papers, most recently
arXiv:0911.4931 and prior PLB 678, 516 (2009)).
At a minimum these works have to be cited in order
to also give credence to a non-QGP interpretation.

Second, the fits:
The fit discussion has an appropriate level of detail
and the power law as well as the mt-exponential
are well explained. It is quite unusual though to
envoke a power-law for low momentum particles and
because of that it would be useful to also quote
the power-law exponential (B) in the table in order
for high energy theorists to relate the applied power
law fit to fits to the higher pt-ranges in high energy
experiments. The low pt enhancement in the pion spectrum
is likely due to resonance decay and that should be
mentioned as well. I believe STAR has written a detailed
paper on the resonance effect in the low pt part of the
pion spectrum. Maybe that reference could be added.

Finally, the data interpretation:
I have read the paragraph relating to Fig.7
(lines 249-262) over and over again (plus the figure
caption of Fig.7, which is a repeat) and I still can't
make sense of it. So I urge the authors to re-write
that paragraph and make the message clearer.
Here are my (mis)understandings:
a.) what are the three equal inverse slopes ??
b.) a simultaneous fit to which spectra ?
c.) giving which single value ?
d.) radial flow depends on 'local' system size...
    what does that mean ?
e.) what is a local system size ?
f.) the difference in inverse slope in the overlapping
region in pbar/p might be due to radial flow velocity ?

I think the authors are trying to say that the systems
at the SPS and RHIC at the same pbar/p have different
shape and potentially different radial flow velocity
and thus the slopes are different. Wouldn't the flow
velocity be different just because the collision
energy is different ? It is not clear to me why that
would depend on the shape at all. I think a re-formulation
with a little more explanation will definitely help.
Also, the text and the figure caption should differ from
each other.

These are my comments. As I said, it's a well written,
important paper which is nicely data driven, and thus
should be published with just slight changes.
Congratulations to the authors.



-- 
Ionut Cristian Arsene
PhD student at Physics Department, University of Oslo, Norway
Phone: +47 22856456 (Office)
Phone: +47 40019590 (Mobile)

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