K(892)* Resonance Production in Au+Au and p+p Collisions at sqrt(sNN) = 200 GeV at RHIC

Abstract

The short-lived $K(892)^{*}$ resonance provides an efficient tool to probe properties of the hot and dense medium produced in relativistic heavy-ion collisions. We report measurements of $K^{*}$ in $\sqrt{s_{_{NN}}}$ = 200 GeV Au+Au and $p+p$ collisions reconstructed via its hadronic decay channels $K(892)^{*0} \to Kπ$ and $K(892)^{*\pm} \to K_S^0π^{\pm}$ using the STAR detector at RHIC. The $K^{*0}$ mass has been studied as a function of $p_T$ in minimum bias $p+p$ and central Au+Au collisions. The $K^{*}$ $p_T$ spectra for minimum bias $p+p$ interactions and for Au+Au collisions in different centralities are presented. The $K^{*}/K$ yield ratios for all centralities in Au+Au collisions are found to be significantly lower than the ratio in minimum bias $p+p$ collisions, indicating the importance of hadronic interactions between chemical and kinetic freeze-outs. A significant non-zero $K^{*0}$ elliptic flow ($v_2$) is observed in Au+Au collisions and compared to the $K_S^0$ and $Λ$ $v_2$. The nuclear modification factor of $K^{*}$ at intermediate $p_{T}$ is similar to that of $K_{S}^{0}$, but different from $Λ$. This establishes a baryon-meson effect over a mass effect in the particle production at intermediate $p_T$ ($2 < p_T \leq 4$ GeV/$c$).