[Brahms-l] RE: meson paper draft

    Dear Djamel,
           here are some comments on the draft. I have tried to work a comprimise on Bjorken. I have also put in the more modern format for author list and added acknowledments. Yours Michael. The comments are listed here but they are also in the text file and attached. 


Dear Djamel, here are my comments. The insert of Fig 4 should have Sqrt(Snn) as the x label. It is something else on my printer. I think it is
better to use the \affiliation for the author list since this letter 
search engines "harvest" the institute information. If there is space I would add a table of the 4pi yields. 
Michael



At forward rapidities, where more net--baryons are
observed~\cite{peter}, other production mechanisms, such as
%MJM strangeness associated production 
 associated production of strangeness 
may compete.

BRAHMS consists of mid--rapidity (MRS) and forward spectrometers (FS)
that measure the momentum, charge and mass of particles, and a set of
global detectors for event characterization 
%MJM delete last line. \cite{nim}.
\cite{nim,myself}

Particle spectra have been obtained by combining several data sets,
each set being characterized by a spectrometer setting (magnetic field
and position), % MJM thus
that is 
 a given portion of the phase--space $(y,p_T)$.

Change 
Yields $dN/dy$  were calculated by integrating the resulting fit
functions over the whole $p_T$ range.
to 

%MJM Yields 
The 
$dN/dy$ yields were calculated by integrating the resulting fit
functions over the whole $p_T$ range.


The difference between kaon and pion
spectral shapes may be accounted for a contribution of resonance
decays producing pions at low $p_T$. 
==>
he difference between kaon and pion
spectral shapes may be accounted for %MJM a 
by the 
contribution of resonance
decays producing pions at low $p_T$.

Change
a sum of Gaussian
(G2) or Woods-Saxon (WS) distributions placed symmetrically around
$y=0$.  
==>
a sum of two  Gaussians %MJM
or two Woods-Saxon  distributions placed symmetrically around
$y=0$. 

You don't need to name the functions since you never use them again.
If you have the space it would be nice to have the 4pi yields as a table at the  back.


%MJM It does not matter if you systematic error depends upon y as long as 
% it is not so large that we cannot discriminate between a flat distribution % and a Gaussian one. 

Change 
Unfortunately, a
non negligible fraction of our systematic error depends on
$y$. Therefore, the present data cannot bring a definitive conclusion
regarding the Bjorken picture. However, they exhibit a nearly Gaussian
rapidity distribution. 
Widths are found to be $\sigma_{\pi^+} = 2.27

==> 
While the Bjorken picture may work reasonably well for |y|<1 it certainly 
fails to describe the full rapidity region. 
Indeed our rapidity distributions are well represented by Gaussians. 
The widths are found to be 


Change
This reminds of the old hydrodynamical expansion
model proposed by L.~D.~Landau fifty years ago~\cite{landau}. 
==>
This is reminiscent of the old hydrodynamical expansion
model proposed by L.~D.~Landau fifty years ago~\cite{landau}.


Delete Eqn 1 and say
the hydrodynamical
equations, using the equation of state of a relativistic gas of
massless particles, leads to a Gaussian dN/dy distribution.  In a simplified ... 

Change 
Figure~\ref{fig:landau}(a) shows $dN/dy(\pi)$ and Landau's prediction
for \snn{200} (using Eq.~\ref{eq:gaus} and 
\ref{eq:width} with the
condition that the integrals of these Gaussians must be equal to the
full--space yields estimated from the data).
==>
Figure~\ref{fig:landau}(a) shows $dN/dy(\pi)$ and Landau's prediction
for \snn{200} (using Eq.~ %MJM\ref{eq:gaus} and 
\ref{eq:width} with the
condition that the integrals of these Gaussians must be equal to the
full--space yields estimated from the data).

The Gaussian distributions got a lot of press at QM04.
I think that the last paragraph should be reordered and the link to Landau 
strengthened. 

In conclusion, BRAHMS has measured the transverse momentum spectra and
inclusive invariant yields of charged meson $\pi^\pm$ and $K^\pm$. The
particle yields show a maximum at mid--rapidity and decrease by more
than a factor 3 at y$> 3$. The rapidity coverage allowed total yields
to be estimated. It has been found that pion rapidity distributions
are relatively well described by Gaussians, the width of which are not
in complete disagreement with the Landau hydrodynamical
model~\cite{landau,carut}. The gross agreement is valid at lower
energies as well, in spite of the difference in the degree of
transparency. The $K/\pi$ ratios are well reproduced by the hadron gas
statistical model~\cite{braun} that assumes strangeness equilibration.
The increasing difference between $K^+$ and $K^-$ yields at higher
rapidities can be explained by a change of the baryo--chemical
potential $\mu_B$ with increasing rapidity. This variation can be
compared with the energy systematics of the $K/\pi$ ratios within such
statistical context.

=>>

In conclusion, BRAHMS has measured the transverse momentum spectra and
inclusive invariant yields of charged meson $\pi^\pm$ and $K^\pm$. The
particle yields show a maximum at mid--rapidity and decrease by more
than a factor 3 at y$> 3$. The rapidity coverage allowed total yields
to be estimated. 
The $K/\pi$ ratios are well reproduced by the hadron gas
statistical model~\cite{braun} that assumes strangeness equilibration.
The increasing difference between $K^+$ and $K^-$ yields at higher
rapidities can be explained by a change of the baryo--chemical
potential $\mu_B$ with increasing rapidity. This variation can be
compared with the energy systematics of the $K/\pi$ ratios within such
statistical context. The pion rapidity distributions
are well described by Gaussians, the width of which are within 5\% 
of the Landau hydrodynamical
model~\cite{landau,carut}. At lower
energies the difference between this model and the data are also ~5\% , in spite of the difference in the degree of
transparency. 




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