K(892)* resonance production in Au+Au and p+p collisions at s(NN)**(1/2) = 200-GeV at STAR

The collaboration
Phys.Rev.C 71 (2005) 064902, 2005.

Abstract (data 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 $sqrt{s_{NN}} =200GeV$ Au+Au and $p+p$ collisions reconstructed via its hadronic decay channels $K(892)^{*0}->K\pi$ and $K(892)^{*\pm}->K_S^0\pi^{\pm}$ 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 $\Lambda$ $v^2$. 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 pT (2<pT<=4GeV/c).

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Data from Figure 2

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$K_S^0$ signal observed in the $\pi^+\pi^−$ invariant mass distribution reconstructed from the decay topology method via $K_S^0->\pi^+\pi^−$ in $p+p$ collisions....

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Data from Figure 5

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The $K\pi$ invariant mass distributions after event-mixing background subtraction (open star symbols) and like-sign background subtraction with different daughter momentum...

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Data from Figure 6

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Data from Figure 9

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Data from Figure 9

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