From: Murray, Michael J (mjmurray@ku.edu)
Date: Tue Jul 08 2003 - 10:38:02 EDT
Dear Ian,
congratulations to everyone for such a great report. Since we
don't yet have the 2nd report is it essential to reply today? While we may
use the same cross section
as everyone else Kopeliovich's reference to CDF results is worrying.
I would propose
confessing that we have not measured the non diffractive pp cross section.
(Is anyone going to measure it here? Maybe pp2pp?)
However I am not sure that even if Kopeliovich was right about the cross
section that
we should renormalise R_AA by a factor of 1.4.
Remember that R_AA = (d2N_AuAu/dPt/dEta)
-------------------
N_bin (d2N_NN/dPt/dEta)
where d2_NN/dPt/dEta = d2Sigma_NN/dPt/dEta/Sigma_pp
Thus if Sigma_pp when down by a factor of 1.4 then d2_NN/dpt/dEta should go
up
by a factor of 1.4.
However Sigma_pp also effects N_bin. Surely if we run the Glauber
calculation with
a smaller sigma_pp then N_bin would go down. It will not go down exactly a
factor of
1.4 since if a projectile nucleon can hit multiple target nucleons.
Why don't we just rerun the Glauber calculation and find out?
Yours Michael
785 864 3949, cell 785 550 8835
We should also mention that changing sigma_pp would
not change anything about R_cp or R_eta. Also Figure 4 shows that the
nuclear
modification factors simply have different shapes for Au+Au and d+Au.
-----Original Message-----
From: Ian Bearden [mailto:bearden@nbi.dk]
Sent: Tue 7/8/2003 7:58 AM
To: brahms-l@bnl.gov
Cc:
Subject: Reply to PRL (re: HighPt)
Dear Collaborators,
Here is my proposed answer to Dr. Malenfant. In the absence of
comments, I will send this at 1200 EDT today.
Best regards,
Ian Bearden
__________________________________________________
Dear Dr. Malenfant,
We are very pleased both with the fantastic response time and with the
very positive referee report.
We have read the lecture notes referred to by referee A. The value of
42 mb for the inelastic pp cross section at 200 GeV (center of mass
energy) is the current best estimate (cf. Particle Data Book). This
value includes, of course, diffractive processes. In our work (I.
Arsene et al. LG8974) we have used published pbar+p data (from UA1) as
a reference, and have compared this to the published p+p data from STAR
and find excellent agreement. We have no reason to doubt that the UA1
and STAR collaborations have corrected appropriately for trigger
inefficiencies (which would correctly take care of the diffractive
events).
We therefore see no reason to alter the text of our manuscript, and
hope that it can proceed rapidly toward publication.
Sincerly,
Ian Bearden
on behalf of the BRAHMS collaboration
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