We present first measurements of the $\phi$-meson elliptic flow ($v_{ 2}(p_{ T})$) and high statistics $p_{ T}$ distributions for different centralities from $\sqrt{ s_{ NN}}$ = 200 GeV Au+Au collisions at RHIC. In minimum bias collisions the $v_{ 2}$ of the $\phi$ meson is consistent with the trend observed for mesons. The ratio of the yields of the $\Omega$ to those of the $\phi$ as a function of transverse momentum is consistent with a model based on the recombination of thermal $s$ quarks up to $p_{ T}\sim 4$ GeV/$c$, but disagrees at higher momenta. The nuclear modification factor ($R_{ CP}$) of $\phi$ follows the trend observed in the $K^{ 0}_{ S}$ mesons rather than in $\Lambda$ baryons, supporting baryon-meson scaling. Since $\phi$-mesons are made via coalescence of seemingly thermalized $s$ quarks in central Au+Au collisions, the observations imply hot and dense matter with partonic collectivity has been formed at RHIC.
Categories: nucl-ex