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Disappearance of partonic collectivity in sNN = 3 GeV Au+Au collisions at RHIC


Abdallah, M. S. ; Aboona, B. E. ; Adam, J. ; Adamczyk, L.; Adams, J. R. ; Adkins, J.; Agakishiev, G.; Aggarwal, I.; Aggarwal, M.; Ahammed, Z; Spinka, H. M.; Zurek, Maria


We report on the measurements of directed flow and elliptic flow for hadrons (, , , p, , and ) from Au+Au collisions at GeV and for (, , p and ) at 27 and 54.4 GeV with the STAR experiment. While at the two higher energy midcentral collisions the number-of-constituent-quark (NCQ) scaling holds, at 3 GeV the at midrapidity is negative for all hadrons and the NCQ scaling is absent. In addition, the slopes at midrapidity for almost all observed hadrons are found to be positive, implying dominant repulsive baryonic interactions. The features of negative and positive slope at 3 GeV can be reproduced with a baryonic mean-field in transport model calculations. These results imply that the medium in such collisions is likely characterized by baryonic interactions.