Abstract: | The PHENIX collaboration at the Relativistic Heavy Ion Collider (RHIC)
reports measurements of azimuthal dihadron correlations near midrapidity in
d+Au collisions at sqrt(s_NN)=200 GeV. These measurements complement recent
analyses by experiments at the Large Hadron Collider (LHC) involving central
p+Pb collisions at sqrt(s_NN)=5.02 TeV, which have indicated strong anisotropic
long-range correlations in angular distributions of hadron pairs. The origin of
these anisotropies is currently unknown. Various competing explanations include
parton saturation and hydrodynamic flow. We observe qualitatively similar
anisotropies at RHIC to those seen at the LHC, and when both are divided by an
estimate of the initial-state eccentricity, the anisotropies follow a common
multiplicity scaling. This scaling is also found to extend to heavy ion data at
RHIC and the LHC, where the anisotropies are widely thought to be due to
hydrodynamic flow. The results presented here, at much lower collision energy
and with a deuteron projectile (instead of a proton), provide important new
information for understanding the origin of these new long-range correlations. |