Deviation from quark-number scaling of the anisotropy parameter v_2 of   pions, kaons, and protons in Au+Au collisions at sqrt(s_NN) = 200 GeV
  Measurements of the anisotropy parameter v_2 of identified hadrons (pions, kaons, and protons) as a function of centrality, transverse momentum p_T, and transverse kinetic energy KE_T at midrapidity (|\eta|<0.35) in Au+Au collisions at sqrt(s_NN) = 200 GeV are presented. Pions and protons are identified up to p_T = 6 GeV/c, and kaons up to p_T = 4 GeV/c, by combining information from time-of-flight and aerogel Cherenkov detectors in the PHENIX Experiment. The scaling of v_2 with the number of valence quarks (n_q) has been studied in different centrality bins as a function of transverse momentum and transverse kinetic energy. A deviation from previously observed quark-number scaling is observed at large values of KE_T/n_q in noncentral Au+Au collisions (20--60%), but this scaling remains valid in central collisions (0--10%). 
A. Adare, S. Afanasiev, C. Aidala, N.N. Ajitanand, Y. Akiba, H.   Al-Bataineh, J. Alexander, K. Aoki, Y. Aramaki, E.T. Atoms...
nucl-ex nucl-th