Measurements of the nuclear modification factor and elliptic flow of ϕ mesons at RHIC

The observation of meson and baryon grouping in the RCP and v2 measurements at intermediate pT has been interpreted as a manifestation of bulk partonic matter hadronization through multi-parton dynamics such as recombination of partons. ϕ mesons provide unique sensitivity to test these theoretical scenarios, since the ϕ has a mass heavier than the proton and close to the hyperons. The RCP and v2 measurements of ϕ mesons from Run IV Au+Au collisions at at STAR are presented. Energy and colliding system dependence of the ϕ 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.