Averaged transverse momentum correlations of hadrons in relativistic heavy-ion collisions

Abstract

We compile experimental data for the averaged transverse momentum ($⟨p_T⟩$) of proton, $\hat{I}›$, $\hat{I}{ž}^{-}$, $\hat{I}{\text{c◯}}^{-}$ and $\ddot{I}•$ at mid-rapidity in Au+Au collisions at $\sqrt{s_{NN}}=$ 200, 39, 27, 19.6, 11.5, 7.7 GeV and in Pb+Pb collisions at $\sqrt{s_{NN}}=$ 2.76 TeV, and find that experimental data of these hadrons exhibit systematic correlations. We apply a quark combination model with equal-velocity combination approximation to derive analytic formulas of hadronic $⟨p_T⟩$ in the case of exponential form of quark $p_T$ spectra at hadronization. We use them to successfully explain the systematic correlations exhibited in $⟨p_T⟩$ data of $p\hat{I}›$, $\hat{I}›\hat{I}{ž}^{-}$, $\hat{I}{ž}^{-}\hat{I}{\text{c◯}}^{-}$ and $\hat{I}{ž}^{-}\ddot{I}•$ pairs. We also use them to successfully explain the regularity observed in $⟨p_T⟩$ of these hadrons as the function of $(d{N}_{ch}/dy)/(N_{part}/2)$ at mid-rapidity in central heavy-ion collisions at both RHIC and LHC energies. Our results suggest that the constituent quark degrees of freedom and the equal-velocity combination of these constituent quarks at hadronization play important role in understanding the production of baryons and $\ddot{I}•$ meson at these RHIC and LHC energies.

10 pages, 7 figures