Multistrange Baryon Production in Au-Au Collisions at $\sqrt{s_{NN}}=130\mathrm{GeV}$

The transverse mass spectra and midrapidity yields for $\Xi$s and $\Omega$s are presented. For the 10% most central collisions, the ${\overline{\Xi }}^{+}/h^{-}$ ratio increases from the Super Proton Synchrotron to the Relativistic Heavy Ion Collider energies while the ${\Xi }^{-}/h^{-}$ stays approximately constant. A hydrodynamically inspired model fit to the $\Xi$ spectra, which assumes a thermalized source, seems to indicate that these multistrange particles experience a significant transverse flow effect, but are emitted when the system is hotter and the flow is smaller than values obtained from a combined fit to $\pi$, $K$, $p$, and $\Lambda$s.

Figure 1

$m_{\perp }$ spectra for (a) ${\Xi }^{-}$, (b) ${\overline{\Xi }}^{+}$, and (c) $\Omega$ as a function of centrality. Scale factors have been applied to the spectra for clarity. Points are drawn at the bin center. The horizontal bars indicate the bin size. The dashed curves are Boltzmann fits to the spectra. The solid curves are hydrodynamically inspired model fits to the most central ${\Xi }^{-}$ and ${\overline{\Xi }}^{+}$ spectra.

Figure 2

(a) ${\Xi }^{-}$, ${\overline{\Xi }}^{+}$, $\Lambda$, and $\overline{\Lambda }$ to $h^{-}$ ratios and (b) ${\Xi }^{-}/\Lambda$ and ${\overline{\Xi }}^{+}/\overline{\Lambda }$ ratios for the most central data as a function of $\sqrt{s_{NN}}$. The solid bars indicate the statistical uncertainty while the caps indicate the statistical and systematic uncertainties added in quadrature. Some ratios are slightly shifted along the x axis for clarity.

Figure 3

(a) $T_{\mathrm{fo}}$ versus $⟨{\beta }_{\perp }⟩$ for the hydrodynamically inspired model fits to the $m_{\perp }$ spectra. The one, two, and three sigma contours are shown. Dashed curves are for a simultaneous fit to the ${\Xi }^{-}$ and ${\overline{\Xi }}^{+}$. Solid curves are a separate fit to the STAR $\pi$, $K$, $p$, and $\Lambda$ data. The diamonds represent the best fit in both cases. (b) $⟨p_{\perp }⟩$ for identified particles versus particle mass (see text for details). The band results from the three sigma contour of the hydrodynamically inspired model fit to the $\pi$, $K$, $p$, and $\Lambda$ data, and the dashed curve is for $T_{\mathrm{fo}}=170\mathrm{MeV}$, $⟨{\beta }_{\perp }⟩=0$.