Speaker
Description
Hydrodynamic expansion and jet quenching are responsible for the production of low and high transverse-momentum (𝑝𝑇) particle in heavy-ion collisions, respectively. However, it is still a challenge to simultaneously describe hadron nuclear modification factor $𝑅_{\rm 𝐴𝐴}$ and elliptic flow $𝑣_2$, especially in the intermediate $𝑝_𝑇$ region of 2$<𝑝_𝑇<10$ GeV/c. In this talk, we combine hydrodynamics, quark coalescence and jet quenching as well as the hadron cascade, and study their effects on hadron spectra and flow. We find the key to solving the $𝑅_{\rm 𝐴𝐴}$−$𝑣_2$ puzzle is the incorporation of quark coalescence into the state-of-the-art event-by-event simulations of heavy-ion collisions. Specifically, our new theoretical framework combines 1) the Coupled Linearized Boltzmann Transport and Hydrodynamic (CoLBT-Hydro) model, 2) a hadronization model including Cooper-Frye sampling, quark coalescence and string fragmentation, and 3) a hadron cascade model. For the first time, we can consistently describe and understand the experimental data on $𝑅_{\rm 𝐴𝐴}$and $𝑣_2$ along with their flavor dependence and hadron chemistry (proton-to-pion and kaon-to-pion ratios) from low to intermediate $𝑝_𝑇$ and high $𝑝_𝑇$ in heavy-ion collisions at both RHIC and LHC energies. Our prediction is an example of high-precision tests of the quark coalescence model in nuclear collisions.
Then I will talk about the quark number scaling of strange quark and light quarks in RHIC and LHC within the Cooper-Frye, quark coalescence and string fragmentation framework. We can simultaneously describe the different quark number scaling behaviors of strange quark and light quarks at RHIC and LHC . We expound that such different NCQ scaling behaviors at these two energies is associated with the different relative weights of quark coalescence and string fragmentation contributions at intermediate $p_T$ range and the strangeness enhancement in the bulk medium. This results can also be used to quantitatively test the quark coalescence model in the future.
[1] Wenbin Zhao, Weiyao Ke, Wei Chen, Tan Luo and Xin-Nian Wang, Phys. Rev. Lett. 128 (2022) no.2, 022302.
[2] Wenbin Zhao, Weiyao Ke, Wei Chen, Tan Luo and Xin-Nian Wang, in preparation.
[3] Wenbin Zhao, Che-Ming Ko, YuXin Liu, Guangyou Qin and Huichao Song, Phys. Rev. Lett. 125, 072301 (2020).
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