Impact parameter dependence of the nuclear modification of J/psi production in d+Au collisions at sqrt(S_NN) = 200 GeV

TL;DR

This paper investigates how the nuclear modification of J/psi production in d+Au collisions at 200 GeV depends on impact parameter, revealing a nonlinear onset of shadowing and a time-dependent absorption process.

Contribution

It introduces a model that separately determines impact parameter dependencies of shadowing and absorption, and shows shadowing onset is highly nonlinear with impact parameter.

Findings

Shadowing onset is highly nonlinear with impact parameter.

Absorption cross section depends only on time spent in the nucleus.

Model describes data across various energies and rapidities.

Abstract

The centrality dependence of sqrt(s_NN)= 200 GeV d+Au {J/\psi} data, measured in 12 rapidity bins that span -2.2 < y < 2.4, has been fitted using a model containing an effective absorption cross section combined with EPS09 NLO shadowing. The centrality dependence of the shadowing contribution was allowed to vary nonlinearly, employing a variety of assumptions, in an effort to explore the limits of what can be determined from the data. The impact parameter dependencies of the effective absorption cross section and the shadowing parameterization are sufficiently distinct to be determined separately. It is found that the onset of shadowing is a highly nonlinear function of impact parameter. The mid and backward rapidity absorption cross sections are compared with lower energy data and, for times of 0.05 fm/c or greater, data over a broad range of collision energies and rapidities are well described by a model in which the absorption cross section depends only on time spent in the nucleus.