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. K.; Agakishiev, G.; Aggarwal, I; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I; Anderson, D. M.; Aparin, A.; Aschenauer, E. C.; Ashraf, M. U.; Atetalla, F. G.; Attri, A.; Averichev, G. S.; Bairathi, V; Baker, W.; Cap, J. G. Ball; Barish, K.; Behera, A.; Bellwied, R.; Bhagat, P.; Bhasin, A.; Bielcik, J.; Bielcikova, J.; Bordyuzhin, I. G.; Brandenburg, J. D.; Brandin, A., V; Bunzarov, I; Butterworth, J.; Cai, X. Z.

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摘要

We report on the measurements of directed flow v(1) and elliptic flow v(2) for hadrons (pi(+/-), K-+/-, K-S(0), p, phi, Lambda and Xi(-)) from Au+Au collisions at root s(NN) = 3GeV and v(2) for (pi(+/-), K-+/-, p and (p) over bar) at 27 and 54.4GeV with the STAR experiment. While at the two higher energy midcentral collisions the number-of-constituent-quark (NCQ) scaling holds, at 3GeV the v(2) at midrapidity is negative for all hadrons and the NCQ scaling is absent. In addition, the v(1) slopes at midrapidity for almost all observed hadrons are found to be positive, implying dominant repulsive baryonic interactions. The features of negative v2 and positive v(1) slope at 3GeV 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.

关键词

PLUS AU COLLISIONS QCD PHASE-TRANSITION QUARK-GLUON PLASMA ELLIPTIC FLOW DIRECTED FLOW EQUATION PERSPECTIVE DEPENDENCE ANISOTROPY SIGNATURE