-----Original Message-----
From: SANDWEISS@hepvms.physics.yale.edu
[mailto:SANDWEISS@hepvms.physics.yale.edu]
Sent: Sunday, November 26, 2000 6:25 AM
To: huang@physics.ucla.edu; rjsnellings@lbl.gov; jmn@rhi2.ph.bham.ac.uk;
sandweiss@hepvms.physics.yale.edu; harris@star.physics.yale.edu
Subject: Pbar/p manuscript

Dear Pbar Godfather Colleague,

Thanks to all for your comments!
After studying the manuscript, the supporting materials, and the recent
e-mails
from the committee, I believe the manuscript should be made available to the
entire collaboration. So, if there is no further objection, this is such a
recommendation to Johm Harris.

I do have a number of comments on the manuscript which are given below but
none that would change the above recommendation.

Now we will receive the comments from the collaboration, discuss them via
e-mail, receive responses from the authors, and if needed, schedule a
conference call. My present guess is that  probably, we can reach
agreement via e-mail but, of course, we will do whatever is needed.


All the best,

Jack
----------------------------------------------------------------------------

J. Sandweiss Comments on Pbar/p manuscript


1) On the ExB correction, I am reasonably satisfied that for the kinematic
   range reported in the paper, the effect is very small. I understand very
   well how the rather delicate V0 reconstruction can be much more sensitive.
   Although, of course, it will be nice to see the more precise analyses.


2) I am somewhat confused about "tracking Efficiency" type of corrections.
   First, there is the statement that detector effects should be the same for
   p and pbar. Then in the pbar annihilation correction, a simulation
   (admittedly with the fast simulator) is used which presumably includes
   pbar "losses" due to true annihilation but also to tracking. Thus there may
   be  a "double counting" of the tracking inefficiencies. Or maybe, I am just
   confused! The fact that the correction corresponds to about the right amount
   of material traversed is not really good proof because the tracking
   efficiencies  are presumably of the order of 90% and the "material
   traversed" agreement is maybe not good to 10%?


3) I am most concerned about the feed down from hyperons. While the statement
   that if the Y/p and Ybar/pbar ratios are equal there would be no effect on
   the reported pbar/p ratio is true, these ratios (y/p and Ybar/pbar) may
   well have   different dependences on centrality (or rapidity and pt
   for that matter). So, the fact that the overall ratios appear to be the
   same may hide some important behaviour.

4) The statement that the small decrease in the pbar/p ratio with centrality
   "is consistent with a picture that in more central nuclear collisions more
   baryons are shifted to the central rapidity region", while not incorrect,
   seems to me to be somewhat of a "reach".

   Not only is the effect in the data rather "modest", but many assumptions,
   for example about the hyperon feed down effects, the production rates
   of pbars, the annihilation of pbars inside the collision zone, etc., must
   be made to draw this conclusion from the small effect seen.