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Title: Directed Flow of Identified Particles in Au+Au Collisions at S-NN=200 GeV at RHIC

Journal Article · · Physical Review Letters

STAR's measurements of directed flow (v{sub 1}) around midrapidity for {pi}{sup {+-}}, K{sup {+-}}, K{sub S}{sup 0}, p, and {bar p} in Au+Au collisions at {radical}s{sub NN} = 200 GeV are presented. A negative v{sub 1}(y) slope is observed for most of produced particles ({pi}{sup {+-}}, K{sup {+-}}, K{sub S}{sup 0}, and {bar p}). In 5%-30% central collisions, a sizable difference is present between the v{sub 1}(y) slope of protons and antiprotons, with the former being consistent with zero within errors. The v{sub 1} excitation function is presented. Comparisons to model calculations (RQMD, UrQMD, AMPT, QGSM with parton recombination, and a hydrodynamics model with a tilted source) are made. For those models which have calculations of v{sub 1} for both pions and protons, none of them can describe v{sub 1}(y) for pions and protons simultaneously. The hydrodynamics model with a tilted source as currently implemented cannot explain the centrality dependence of the difference between the v{sub 1}(y) slopes of protons and antiprotons.

Research Organization:
Brookhaven National Lab. (BNL), Upton, NY (United States). Relativistic Heavy Ion Collider (RHIC)
Sponsoring Organization:
USDOE SC OFFICE OF NUCLEAR PHYSICS
DOE Contract Number:
DE-AC02-98CH10886
OSTI ID:
1046984
Report Number(s):
BNL-98060-2012-JA; PRLTAO; R&D Project: PO-003; KB0202012; TRN: US1203830
Journal Information:
Physical Review Letters, Vol. 108, Issue 20; ISSN 0031-9007
Country of Publication:
United States
Language:
English