Measurements of the nuclear modification factor and elliptic flow of   $\phi$ mesons at RHIC
  The observation of meson and baryon grouping in the $R_{CP}$ and $v_2$ measurements at intermediate $p_T$ has been interpreted as a manifestation of bulk partonic matter hadronization through multi-parton dynamics such as recombination of partons. $\phi$ mesons provide unique sensitivity to test these theoretical scenarios, since the $\phi$ has a mass heavier than the proton and close to the hyperons. The $R_{CP}$ and $v_2$ measurements of $\phi$ mesons from Run IV Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV at STAR are presented. Energy and colliding system dependence of the $\phi$ yields at mid-rapidity are discussed. The results are compared to the measurements of other hadrons. Properties of strange quarks in the bulk matter at hadron formation are discussed. 
Xiangzhou Cai (for the STAR Collaboration)