From: Ian Bearden (bearden@nbi.dk)
Date: Mon Jun 30 2003 - 11:35:35 EDT
On mandag, jun 30, 2003, at 17:13 Europe/Copenhagen, Fouad Rami wrote: > > > Hi all, > > The present draft version (June 29) looks very good. > > I have only 2 comments concerning Fig.3: > > 1) Last paragraph, page 4 -> "The figure shows that, within errors, > the > degree of high-pt suppression (at pt > 2GeV/c) observed at eta=2 is > similar or larger than at eta=0". > I don't like "similar" in this sentence. > Fig.3 shows clearly stronger suppression at eta=2 in the high pt > region > (pt > 2GeV/c); it is not "similar". Look at the figure, all 3 points > above 2GeV/c are significantly lower, within error bars, than the > value > at low pt. At pt~3GeV/c, there is almost a factor of 2. > I don't know what this could mean in terms of physics (rather > unexpected!), but this is what the data in Fig.3 are telling us and > those data are free from systematic uncertainties! > I think that this effect should be stated clearly in the paper and > not > just as "similar or larger". It is larger ... > One thing that it could be is antiprotons. PHENIX has shown that protons are not suppressed vs pt. This effect could be in part due to the fact that we compare (h+h-)/2 to h-. So, if pbar(eta=2)<(pbar(eta=0)+p(eta=0))/2, we would expect to see such an effect over and above (or should it be under and below?) the high-pt suppression of mesons. > 2) The second comment is rather a question to Claus and the high-pt > team. > Can we say something on the y-dependence of the high pt suppression > from > the R_AA ratio (Fig.2), by comparing for example the right/left > panels > in the upper part (central events) of the figure ? > Is it consistent with what we observe in Fig.3 ? > If this is the case, then we should mention it in the manuscript. > This would strengthen the message in the paper: same effect > observed consistently from the analysis of 2 different observables > (R_AA and R_cp). > I know that because of the lack of p+p reference at eta=2, the R_AA > ratio at eta=2 is somewhat model-dependent (it relies on Hijing) and > it > is therefore subjected to much larger systematic uncertainties etc. > Nervertheless, if we show R_AA at both rapidities (eta=0 and 2), then > it is legitimate to ask whether the ratio R_AA(eta=2)/R_AA(eta=0) > is consistent with the trend observed in Fig.3 ? I have tried to get this figure made for months, with no success. I think that it might be interesting, except that the errors will be so large that there will be no clear message. I would rather stick with the measure data (i.e R_eta). Thanks for the comments! Cheers, Ian > > Best regards, Fouad > > ----------------------------------------------------------------------- > Fouad RAMI e-mail: fouad.rami@ires.in2p3.fr > IReS phone : 33.(0)3.88.10.62.00 > 23,rue du Loess : 33.(0)3.88.10.64.55 > B.P.28-BAT.20 (secretary's office) > 67037 Strasbourg Cedex 2 fax : 33.(0)3.88.10.66.14 > France > ----------------------------------------------------------------------- > > > > >
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