Measurements of $\varphi$ meson production in relativistic heavy-ion collisions at RHIC

Abstract

We present results for the measurement of $\varphi$ meson production via its charged kaon decay channel $\varphi \to K^{+}{K}^{-}$ in Au+Au collisions at $\sqrt{s_{{}_{NN}}}=62.4$, 130, and 200 GeV, and in $p+p$ and $d$+Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV from the STAR experiment at the BNL Relativistic Heavy Ion Collider (RHIC). The midrapidity ($|y|<0.5$) $\varphi$ meson transverse momentum ($p_T$) spectra in central Au+Au collisions are found to be well described by a single exponential distribution. On the other hand, the $p_T$ spectra from $p+p$, $d$+Au and peripheral Au+Au collisions show power-law tails at intermediate and high $p_T$ and are described better by Levy distributions. The constant $\varphi /K^{-}$ yield ratio vs beam species, collision centrality and colliding energy is in contradiction with expectations from models having kaon coalescence as the dominant mechanism for $\varphi$ production at RHIC. The $\Omega /\varphi$ yield ratio as a function of $p_T$ is consistent with a model based on the recombination of thermal $s$ quarks up to $p_T\sim 4$ GeV/$c$, but disagrees at higher transverse momenta. The measured nuclear modification factor, $R_{dAu}$, for the $\varphi$ meson increases above unity at intermediate $p_T$, similar to that for pions and protons, while $R_{AA}$ is suppressed due to the energy loss effect in central Au+Au collisions. Number of constituent quark scaling of both $R_{cp}$ and $v_2$ for the $\varphi$ meson with respect to other hadrons in Au+Au collisions at $\sqrt{s_{{}_{NN}}}$=200 GeV at intermediate $p_T$ is observed. These observations support quark coalescence as being the dominant mechanism of hadronization in the intermediate $p_T$ region at RHIC.

22 pages, 21 figures, 4 tables

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• Systematic Measurements of Identified Particle Spectra in pp, d+Au and Au+Au Collisions from STAR
• Thermal Dileptons at LHC
• Heavy-Quark Kinetics in the QGP at LHC
• Partonic flow and $\varphi$-meson production in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV
• phi photo-production from Li, C, Al, and Cu nuclei at Egamma=1.5 - 2.4 GeV
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