We analyze the recent data from the BRAHMS Collaboration on the pseudorapidity dependence of nuclear modification factors in Au+Au collisions at $\sqrt{ s_{ NN}}$ = 200 GeV by using the full three dimensional hydrodynamic simulations for the density effects on parton energy loss. We first compute the transverse spectra at $\eta=0$ and 2.2, and next take a ratio $R_{ \eta}=R_{ AA}(\eta=2.2)/R_{ AA}(\eta=0)$, where $R_{ AA}$ is a nuclear modification factor. It is shown that hydrodynamic components account for $R_{ \eta}\simeq 1$ at low $p_\mathrm{ T}$ and that quenched pQCD components lead $R_{ \eta} < 1$ at high $p_\mathrm{ T}$ which are consistent with the data. Strong suppression at $\eta=2.2$ is compatible with the parton energy loss in the final state.
Categories: nucl-th hep-ph nucl-ex