Elliptic flow of identified hadrons in Au+Au collisions at √s[subscript NN]=7.7-62.4 GeV

• Main Authors: Balewski, Jan T. (Contributor), Betancourt, Michael Joseph (Contributor), Corliss, Ross (Contributor), Hays-Wehle, James Prewitt (Contributor), Leight, William Axel (Contributor), Stevens, Justin (Contributor), van Nieuwenhuizen, Gerrit Jan (Contributor)
• Other Authors: Massachusetts Institute of Technology. Laboratory for Nuclear Science (Contributor)
• Format: Article
• Language: English
• Published: American Physical Society, 2013-10-07T15:43:26Z.
• Subjects: Article
• Online Access: Get fulltext

 Measurements of the elliptic flow, v[subscript 2], of identified hadrons (π[superscript ±], K[superscript ±], K[0 over s], p, p̅ , ϕ, Λ, Λ̅ , Ξ[superscript −], Ξ̅ [superscript +], Ω[superscript −], Ω̅ [superscript +]) in Au+Au collisions at √s[subscript NN]=7.7, 11.5, 19.6, 27, 39, and 62.4 GeV are presented. The measurements were done at midrapidity using the time-projection chamber and the time-of-flight detectors of the Solenoidal Tracker at RHIC experiment during the beam-energy scan program at Relativistic Heavy Ion Collider. A significant difference in the v[subscript 2] values for particles and the corresponding antiparticles was observed at all transverse momenta for the first time. The difference increases with decreasing center-of-mass energy, √s[subscript NN] (or increasing baryon chemical potential, μ[subscript B]), and is larger for the baryons as compared to the mesons. This implies that particles and antiparticles are no longer consistent with the universal number-of-constituent quark (NCQ) scaling of v[subscript 2] that was observed at √s[subscript NN]=200 GeV. However, for the selected group of particles (π[superscript +], K[superscript +], K[0 over s], p, Λ, Ξ[superscript −], Ω[superscript −]) NCQ scaling at (m[subscript T]−m[subscript 0])/nq>0.4 GeV/c[superscript 2] is not violated within ±10%. The v[subscript 2] values for ϕ mesons at 7.7 and 11.5 GeV are approximately two standard deviations from the trend defined by the other hadrons at the highest measured p[subscript T] values.