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

Abstract

The short-lived $K(892{)}^{\ast }$ resonance provides an efficient tool to probe properties of the hot and dense medium produced in relativistic heavy-ion collisions. We report measurements of $K^{\ast }$ in $\sqrt{s_{{}_{NN}}}$ = 200 GeV Au+Au and $p+p$ collisions reconstructed via its hadronic decay channels $K(892{)}^{\ast 0}\to K\ddot{I}€$ and $K(892{)}^{\ast \pm }\to K_S^0\ddot{I}{€}^{\pm }$ using the STAR detector at RHIC. The $K^{\ast 0}$ mass has been studied as a function of $p_T$ in minimum bias $p+p$ and central Au+Au collisions. The $K^{\ast }$ $p_T$ spectra for minimum bias $p+p$ interactions and for Au+Au collisions in different centralities are presented. The $K^{\ast }/K$ 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 $K^{\ast 0}$ elliptic flow ($v_2$) is observed in Au+Au collisions and compared to the $K_S^0$ and $\hat{I}›$ $v_2$. The nuclear modification factor of $K^{\ast }$ at intermediate $p_T$ is similar to that of $K_S^0$, but different from $\hat{I}›$. This establishes a baryon-meson effect over a mass effect in the particle production at intermediate $p_T$ ($2<p_T\le 4$ GeV/$c$).

16 pages, 16 figures, accepted by PRC for publication