Abstract
We present a new analysis of production yields in deuteron-gold collisions at GeV using data taken from the PHENIX experiment in 2003 and previously published in S. S. Adler et al. [Phys. Rev. Lett 96, 012304 (2006)]. The high statistics proton-proton data taken in 2005 are used to improve the baseline measurement and thus construct updated cold nuclear matter modification factors (). A suppression of in cold nuclear matter is observed as one goes forward in rapidity (in the deuteron-going direction), corresponding to a region more sensitive to initial-state low- gluons in the gold nucleus. The measured nuclear modification factors are compared to theoretical calculations of nuclear shadowing to which a (or precursor) breakup cross section is added. Breakup cross sections of mb are obtained by fitting these calculations to the data using two different models of nuclear shadowing. These breakup cross-section values are consistent within large uncertainties with the mb determined at lower collision energies. Projecting this range of cold nuclear matter effects to copper-copper and gold-gold collisions reveals that the current constraints are not sufficient to firmly quantify the additional hot nuclear matter effect.
6 More- Received 26 November 2007
DOI:https://doi.org/10.1103/PhysRevC.77.024912
©2008 American Physical Society