K(892)(*) resonance production in Au+Au and p+p collisions at root s(NN)=200 GeV

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 root s(NN)=200 GeV Au+Au and p+p collisions reconstructed via its hadronic decay channels K(892)*(0)-> K pi and K(892)*(+/-)-> K(S)(0)pi(+/-) using the STAR detector at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. 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 nonzero K*(0) elliptic flow (v(2)) is observed in Au+Au collisions and is compared to the K-S(0) and Lambda v(2). The nuclear modification factor of K* at intermediate p(T) is similar to that of K-S(0) but different from Lambda. This establishes a baryon-meson effect over a mass effect in the particle production at intermediate p(T) (2 < p(T)<= 4 GeV/c).