Cold Nuclear Matter Effects On J/ψ Production As Constrained By Deuteron-Gold Measurements At sNN=200 GeV
Physical Review C
We present a new analysis of J/ψ production yields in deuteron-gold collisions at √sNN=200 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 J/ψ data taken in 2005 are used to improve the baseline measurement and thus construct updated cold nuclear matter modification factors (RdAu). A suppression of J/ψ 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-ₓ gluons in the gold nucleus. The measured nuclear modification factors are compared to theoretical calculations of nuclear shadowing to which a J/ψ (or precursor) breakup cross section is added. Breakup cross sections of σbreakup=2.8₋₁.₄⁺¹'⁷ (2.2₋₁.₅⁺¹'⁶) 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 4.2±0.5 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.
Adare, Andrew Marshall; Baksay, Gyöngyi; Baksay, László A.; Dehmelt, Klaus; Hohlmann, Marcus; Rembeczki, S.; and PHENIX Collaboration, "Cold Nuclear Matter Effects On J/ψ Production As Constrained By Deuteron-Gold Measurements At sNN=200 GeV" (2008). Aerospace, Physics, and Space Science Faculty Publications. 392.