Cold Nuclear Matter Effects on J/ψ Yields as a Function of Rapidity and Nuclear Geometry in d + A Collisions at SNN~(1/2)= 200 GeV

摘要

We present measurements of J/ψ yields in d + Au collisions at SNN~(1/2)= 200 GeV recorded by the PHENIX experiment and compare them with yields in p + p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/ψ rapidity (- 2.2 < y < 2.4) with high statistical precision and are compared with two theoretical models: one with nuclear shadowing combined with final state breakup and one with coherent gluon saturation effects. In order to remove model dependent systematic uncertainties we also compare the data to a simple geometric model. The forward rapidity data are inconsistent with nuclear modifications that are linear or exponential in the density weighted longitudinal thickness, such as those from the final state breakup of the bound state.