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Abstract: We present the first measurements of charge-dependent correlations on angular difference variables (pseudorapidity) and (azimuth) for primary charged hadrons with transverse momentum and from Au–Au collisions at . We observe correlation structures not predicted by theory but consistent with evolution of hadron emission geometry with increasing centrality from one-dimensional fragmentation of color strings along the beam direction to an at least two-dimensional hadronization geometry along the beam and azimuth directions of a hadron-opaque bulk medium. [Copyright &y& Elsevier]

Abstract: Identified mid-rapidity particle spectra of , , and from 200 GeV and collisions are reported. A time-of-flight detector based on multi-gap resistive plate chamber technology is used for particle identification. The particle-species dependence of the Cronin effect is observed to be significantly smaller than that at lower energies. The ratio of the nuclear modification factor () between protons () and charged hadrons (h) in the transverse momentum range is measured to be in minimum-bias collisions and shows little centrality dependence. The yield ratio of in minimum-bias collisions is found to be a factor of 2 lower than that in collisions, indicating that the Cronin effect alone is not enough to account for the relative baryon enhancement observed in heavy ion collisions at RHIC. [Copyright &y& Elsevier]

Abstract: We report the STAR measurement of ϕ meson production in and collisions at . Using the event mixing technique, the ϕ spectra and yields are obtained at mid-rapidity for five centrality bins in collisions and for non-singly-diffractive collisions. It is found that the ϕ transverse momentum distributions from collisions are better fitted with a single-exponential while the spectrum is better described by a double-exponential distribution. The measured nuclear modification factors indicate that ϕ production in central collisions is suppressed relative to peripheral collisions when scaled by the number of binary collisions . The systematics of versus centrality and the constant ratio versus beam species, centrality, and collision energy rule out kaon coalescence as the dominant mechanism for ϕ production. [Copyright &y& Elsevier]