Nuclear modification factors of φ mesons in d + Au, Cu + Cu, and Au + Au collisions at √ sNN = 200 GeV

PHENIX Collaboration

Enokizono A.

Hachiya T.

Harada H.

Haruna K.

Homma Kensuke

Horaguchi T.

Iwanaga Y.

Kijima K. M.

Nakamiya Y.

Nakamura T.

Nihashi M.

Ouchida M.

Sakata H.

Shigaki Kenta

Sugitate Toru

Torii H.

Tsuchimoto Y.

Watanabe D.

Yamaura K.

Physical Review C

The PHENIX experiment at the Relativistic Heavy Ion Collider has performed systematic measurements of φ meson production in the K+K− decay channel at midrapidity in p + p, d + Au, Cu + Cu, and Au + Au collisions at √sNN = 200 GeV. Results are presented on the φ invariant yield and the nuclear modification factor RAA for Au + Au and Cu + Cu, and RdA for d + Au collisions, studied as a function of transverse momentum (1 < pT < 7 GeV/c) and centrality. In central and midcentral Au + Au collisions, the RAA of φ exhibits a suppression relative to expectations from binary scaled p + p results. The amount of suppression is smaller than that of the π0 and the η in the intermediate pT range (2–5 GeV/c), whereas, at higher pT , the φ, π0, and η show similar suppression. The baryon (proton and antiproton) excess observed in central Au + Au collisions at intermediate pT is not observed for the φ meson despite the similar masses of the proton and the φ. This suggests that the excess is linked to the number of valence quarks in the hadron rather than its mass. The difference gradually disappears with decreasing centrality, and, for peripheral collisions, the RAA values for both particle species are consistent with binary scaling. Cu + Cu collisions show the same yield and suppression as Au + Au collisions for the same number of Npart. The RdA of φ shows no evidence for cold nuclear effects within uncertainties.

Physics [ 420 ]

eng

American Physical Society

Copyright (c) 2011 American Physical Society

[ISSN] 0556-2813

[ISSN] 2469-9985

[NCID] AA00773613

[DOI] 10.1103/PhysRevC.83.024909