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

TL;DR

This paper analyzes transverse momentum correlations of various hadrons in heavy-ion collisions across different energies, using a quark combination model to explain experimental data and reveal underlying quark-level dynamics.

Contribution

It introduces an analytic formula based on a quark combination model to explain systematic $p_T$ correlations in heavy-ion collision data, highlighting the role of constituent quarks.

Findings

Successfully explains $p_T$ correlations in hadron pairs.

Reveals regularity in $p_T$ as a function of charged particle density.

Supports the importance of constituent quark degrees of freedom.

Abstract

We compile experimental data for the averaged transverse momentum ($\left\langle p_{T}\right\rangle $) of proton, $\Lambda$, $\Xi^{-}$, $\Omega^{-}$ and $\phi$ 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 $\left\langle p_{T}\right\rangle $ in the case of exponential form of quark $p_{T}$ spectra at hadronization. We use them to successfully explain the systematic correlations exhibited in $\left\langle p_{T}\right\rangle $ data of $p\Lambda$, $\Lambda\Xi^{-}$, $\Xi^{-}\Omega^{-}$ and $\Xi^{-}\phi$ pairs. We also use them to successfully explain the regularity observed in $\left\langle p_{T}\right\rangle $ of these hadrons as the function of $(dN_{ch}/dy)/(N_{part}/2)$ 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 $\phi$ meson at these RHIC and LHC energies.