We report $J/\psi$ spectra for transverse momenta $p_T$> 5 GeV/$c$ at mid-rapidity in p+p and Au+Au collisions at sqrt(s_{NN}) = 200 GeV.The inclusive $J/\psi$ spectrum and the extracted $B$-hadron feed-down are compared to models incorporating different production mechanisms. We observe significant suppression of the $J/\psi$ yields for $p_T$> 5 GeV/$c$ in 0-30% Au+Au collisions relative to the p+p yield scaled by the number of binary nucleon-nucleon collisions in Au+Au collisions. In 30-60% collisions, no such suppression is observed.The level of suppression is consistently less than that of high-$p_T$ $\pi^{\pm}$ and low-$p_T$ $J/\psi$.
(Color online.) The invariant $J/\psi$ cross section versus $p_{T}$ in p+p collisions at $\sqrt{s}$ = 200 GeV. The vertical bars and boxes depict the statistical and systematic uncertainties, respectively. Also shown are results published by STAR [15] and PHENIX [20]. The curves show theoretical calculations described in the text.
(Color online.) The fraction of $B \rightarrow J/\psi$ over the inclusive $J/\psi$ yield in $p+p$ collisions. The FONLL+CEM model calculation is also shown.
$J/\psi$ $p_{T}$ distributions in Au+Au collisions with different centralities at $\sqrt{s_{NN}}$ = 200 GeV. For clarity, the data and curves have been scaled as indicated in the legends. The PHENIX results are reported in [6]. The curves are model fits described in the text.
We present strange particle spectra and yields measured at mid-rapidity in $\sqrt{\text{s}}=200$ GeV proton-proton ($p+p$) collisions at RHIC. We find that the previously observed universal transverse mass ($\mathrm{m_{T}}\equiv\sqrt{\mathrm{p_{T}}^{2}+\mathrm{m}^{2}}$) scaling of hadron production in $p+p$ collisions seems to break down at higher \mt and that there is a difference in the shape of the \mt spectrum between baryons and mesons. We observe mid-rapidity anti-baryon to baryon ratios near unity for $\Lambda$ and $\Xi$ baryons and no dependence of the ratio on transverse momentum, indicating that our data do not yet reach the quark-jet dominated region. We show the dependence of the mean transverse momentum (\mpt) on measured charged particle multiplicity and on particle mass and infer that these trends are consistent with gluon-jet dominated particle production. The data are compared to previous measurements from CERN-SPS, ISR and FNAL experiments and to Leading Order (LO) and Next to Leading order (NLO) string fragmentation model predictions. We infer from these comparisons that the spectral shapes and particle yields from $p+p$ collisions at RHIC energies have large contributions from gluon jets rather than quark jets.
Corrected mid-rapidity (|y| < 0.5) pT spectra for $K^{+}$, $K^{−}$, $K^{0}_{S}$, Λ, Ξ, and Ω. Λ spectra that have been corrected for feed-down are shown as open symbols in the Λ panel. The dashed lines are fits using Equation 11 except for the $\Omega+\overline{\Omega}$ where the fit uses Equation 9. The error bars displayed include systematic errors while the fits were done using statistical errors only for all species except the charged kaons.
Corrected mid-rapidity (|y| < 0.5) pT spectra for $K^{+}$, $K^{−}$, $K^{0}_{S}$, Λ, Ξ, and Ω. Λ spectra that have been corrected for feed-down are shown as open symbols in the Λ panel. The dashed lines are fits using Equation 11 except for the $\Omega+\overline{\Omega}$ where the fit uses Equation 9. The error bars displayed include systematic errors while the fits were done using statistical errors only for all species except the charged kaons.
Corrected mid-rapidity (|y| < 0.5) pT spectra for $K^{+}$, $K^{−}$, $K^{0}_{S}$, Λ, Ξ, and Ω. Λ spectra that have been corrected for feed-down are shown as open symbols in the Λ panel. The dashed lines are fits using Equation 11 except for the $\Omega+\overline{\Omega}$ where the fit uses Equation 9. The error bars displayed include systematic errors while the fits were done using statistical errors only for all species except the charged kaons.
Forum