From: Joe Natowitz (natowitz@comp.tamu.edu)
Date: Thu Jul 10 2003 - 17:15:37 EDT
I have been talking to Carl Gagliardi here at TAMU. He is part of STAR. He raised a question about the following statement in the latest PRL regarding normalizations. "Also shown in the figure is our measured spectrum from d+Au collisions. The reference is from p + ¯p collisions measured in the range || < 2.5 by the UA1 experiment at CERN [13]. To compare with our spectra we apply a pT and dependent correction estimated using the HIJING (v. 1.383) code [14], which reproduces the main features of p + p collisions well. We have compared our corrected spectrum at = 0 with the ps=200 GeV p+p distribution recently measured by the STAR collaboration [15] and find excellent agreement. " Carl is surprised because in ArXiv / 0305015 - they point out the following. "The charged hadron invariant cross section has been measured in ¯p + p collisions at ps=200 GeV [23]. (THIS IS UA1-our reference 15) The p+p cross section reported here is smaller by a factor of 0.82 ± 0.18, approximately independent of pT , where the uncertainty includes the two spectrum normalizations and the correction for different acceptances [3]. The difference is due in large part to differing NSD cross section, which is 35 ± 1 mb in [23] but is measured here to be 30.9 ± 3.5 mb." He believes that comparison of our results with STAR on a per event basis might show agreement but that the cross section from STAR is different from UA1 and shifts the normalization. This is different from the Kopeliovich question. > Comments ? Joe --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.495 / Virus Database: 294 - Release Date: 6/30/2003
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