arXiv subjects

Chaowen Wang

Publications and source records attributed to Chaowen Wang.

3 recordsLinked to original sources

arXiv2019

Probing the transport properties of Quark-Gluon Plasma via heavy-flavor Boltzmann and Langevin dynamics

The heavy quark propagation behavior inside the quark-gluon plasma (QGP), is usually described in terms of the Boltzmann dynamics, which can be reduced to the Langevin approach by assuming a small momentum transfer for the scattering processes between heavy quarks and the QGP constituents. In this work, the temperature and energy dependence of the transport coefficients are calculated in the framework of both Boltzmann and Langevin dynamics. The derived transport coefficients are found to be systematically larger in the Boltzmann approach as compared with the Langevin, in particular in the high temperature and high energy region. Within each of the two theoretical frameworks, we simulate the charm quark production and the subsequent evolution processes in relativistic heavy-ion collisions. We find that the total in-medium energy loss is larger from the Langevin dynamics, resulting in a smaller (larger) $R_{\rm AA}$ at high (low) $p_{\rm T}$, for both the charm quark and heavy-flavor mesons. Meanwhile, the Boltzmann model is found to induce larger $v_{\rm 2}$, in particular at moderate $p_{\rm T}$, as well as stronger broadening behavior for the azimuthal distributions. By comparing the model calculations with available experimental measurements for D-mesons, we find that the Langevin approach is more favored by the $R_{\rm AA}$ data while the Boltzmann approach is more favored favor by the $v_{\rm 2}$ data. A simultaneous description of both observables appear challenging for both models.

hep-ph↗

arXiv2018

Charm-strange meson production in ultra-relativistic heavy-ion collisions at the CERN-LHC energies

The nuclear modification factor ${R}_{\rm AA}$ and the elliptic flow coefficient ${v}_{\rm 2}$ of charm-strange meson $D^{+}_{s}$ is systematically studied in Pb--Pb collisions at $\sqrt{s_{\rm NN}}=5.02~{\rm TeV}$ and $2.76~{\rm TeV}$. During the modeling, the coupling strength between the injected charm quark and the incident medium constituents, is extracted from the lattice QCD calculations: $2πTD_{s}=7$ (\textbf{Model-A}) and $2πTD_{s}=1.3 + (T/T_{c})^2$ (\textbf{Model-B}). We find that, comparing ${R}_{\rm AA}(D^{+}_{s})$ with ${R}_{\rm AA}(non-strange)$, the heavy-light coalescence effect is more pronounced for the former one, resulting in an enhancement behavior in the range $2\lesssim {p}_{\rm T}\lesssim5~{\rm GeV}$. The predictions of ${R}_{\rm AA}(D^{+}_{s})$ and ${R}_{\rm AA}(non-strange)$ favor Model-A to have a better description of the measured ${p}_{\rm T}$ dependence in both energies, while their ${v}_{\rm 2}$ prefer Model-B at moderate ${p}_{\rm T}$ ($2\lesssim {p}_{\rm T}\lesssim4~{\rm GeV}$). Therefore, it is necessary to consider the temperature- and/or momentum-dependence of $2πTD_{s}$ to describe simultaneously ${R}_{\rm AA}(D^{+}_{s})$ and ${v}_{\rm 2}(D^{+}_{s})$ in different centrality classes in Pb--Pb collisions.

hep-ph↗

arXiv2018

Production of open-charm mesons in relativistic heavy-ion collisions

We present a theoretical framework to study open charm production in relativistic heavy-ion collisions. The coupling strength between the charm quarks and the QGP constituents, quantified by the spatial diffusion coefficient $2πTD_{s}$, is obtained by performing a phenomenological fit analysis to the lattice QCD calculations, resulting in $2πTD_{s}=const.$ (\textbf{Model-A}) and $2πTD_{s}=1.3 + (T/T_{c})^2$ (\textbf{Model-B}). We find that the relative azimuthal distribution of the initially back-to-back generated $c\bar{c}$ pairs presents a broadening behaviour, which is more pronounced for $c\bar{c}$ pairs with small initial $p_{\rm T}$, and when the Model-B approach is adopted. The competition between the initial drag and the subsequent collective effects tends to restrict the time dependence of charm quark $R_{\rm AA}$. Concerning the theoretical uncertainty on final D-meson nuclear modification, the nuclear shadowing and pp baseline components are dominat at high and low $p_{\rm T}$ ($p_{\rm T}\lesssim3~{\rm GeV/{\it c}}$), respectively. The measured D-meson $R_{\rm AA}(p_{\rm T})$ favors Model-A assumption for the diffusion coefficient both at RHIC and LHC, while their $v_{2}(p_{\rm T})$ prefer Model-B at moderate $p_{\rm T}$. These results confirm the necessity to consider the temperature- and/or momentum-dependence of $2πTD_{s}$ to describe well the D-meson $R_{\rm AA}$ and $v_{\rm 2}$ simultaneously.

hep-ph↗