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Zi-Xuan Xu

Publications and source records attributed to Zi-Xuan Xu.

4 recordsLinked to original sources

D-meson production via sequential hadronization in high-energy nuclear collisions

Heavy flavor production serves as an ideal probe of the hadronization mechanism of the quark-gluon plasma created in relativistic heavy ion collisions. We study charm-quark hadronization using Langevin transport in the medium together with a sequential coalescence model. Since $D_s$ forms earlier than $D^0$, as obtained from the Dirac equation with an in-medium potential extracted from lattice QCD, the $D_s$ elliptic flow $v_2$ is smaller than the $D^0$ $v_2$ in the intermediate-$p_T$ region, in good agreement with the recent ALICE data. Incorporating sequential coalescence, charm-quark number conservation, and strangeness enhancement predicts a peak in the yield ratio $D_s/D^0$ at low $p_T$, which can be tested in future heavy-ion collisions.

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Bayesian Inference of Heavy-Quark Dissipation and Jet Transport Parameters from D-Meson observables in heavy-ion collisions at the LHC energies

We perform the first simultaneous Bayesian inference of the temperature-dependent heavy-quark spatial diffusion coefficient $2πT\mathcal{D}_s$ and the scaled jet transport coefficient $\hat{q}/T^3$ in the quark-gluon plasma, utilizing $D$-meson nuclear modification factor $R_\text{AA}$ and elliptic flow $v_2$ data from Pb-Pb collisions at $\sqrt{s_\text{NN}} = 5.02\ \text{TeV}$. The analysis employs a unified improved Langevin transport model that incorporates both collisional and radiative energy loss, followed by coalescence plus fragmentation hadronization. The posterior distributions of the parameters of $\hat{q}/T^3$ and those of $2πT\mathcal{D}_s$ are well constrained, and compared with the results of theoretical models or other experimental data extraction, respectively. The $30-50\%$ centrality data provide significantly stronger constraints than the $0-10\%$ data. The extracted ratio $\hat{q}/κ$ between the quark jet transport and heavy-quark diffusion coefficients exhibits a non-monotonic temperature dependence, deviating from the value $2$ estimated from the definition, with a value interval spanning 0.25--0.8 corresponding to the mean values of the inferred parameters. This work establishes a data-driven quantitative relationship between these two fundamental transport properties in the same observables, offering crucial insight into their interplay in the strongly coupled medium.

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Study of the EEC discrimination power on quark and gluon jet quenching effects in heavy-ion collisions at $\sqrt{s}=5.02$ TeV

We present a systematic investigation of flavor-dependent jet quenching using energy-energy correlators (EEC) in $\sqrt{\rm s}=5.02$ TeV Pb+Pb collisions. Employing the improved SHELL model, which incorporates collisional and radiative energy loss, as well as medium response, we quantify distinct quenching signatures for quark and gluon jets. Key findings include: (1) Pure quark jets exhibit strong EEC enhancement at large angular scales, while gluon jets show a bimodal enhancement pattern at both small and large scales; (2) Dual-shift decomposition in the EEC ratio reveals shifts toward large primarily driven by energy loss, while small-$R_{L}$~shifts extend beyond selection bias and indicate intrinsic enhancement of the gluon-initiated jets; (3) Quark jets experience global suppression of averaged energy weight $\langle\mathrm{weight}\rangle(R_{L})$, whereas gluon jets exhibit concentration toward small $R_{L}$; (4) Mechanism decomposition identifies elastic energy loss concentrating $\langle\mathrm{weight}\rangle(R_{L})$ toward small $R_{L}$, radiative loss dominating quark jet modification, and medium response amplifying large $R_{L}$ ~enhancement via soft hadrons. The observed flavor dependence in EEC modifications is dominantly driven by intrinsic jet structure differences rather than medium-induced mechanisms. We propose photon-tagged jets as quark proxies and inclusive charged-hadron jets as gluon proxies, finding they reproduce the respective flavor-specific quenching patterns. Our work establishes the EEC as a precision probe of color-charge-dependent jet-medium interactions, providing new constraints for the detailed $\hat{q}$ extraction and QGP tomography, while highlighting the critical role of pre-quenching flavor asymmetries.

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Substructures of heavy flavor jets in $pp$ and PbPb collisions at $\sqrt{s}$ = 5.02 TeV

Groomed jet substructure measurements, the momentum splitting fraction $z_g$ and the groomed jet radius $R_g$, of inclusive, D$^0$-tagged and B$^0$-tagged jets in $pp$ and central PbPb collisions at $\sqrt{s}=5.02$ TeV are predicted and investigated. Charged jets are constrained in a relatively low transverse momentum interval 15 $\leq p_{\rm T}^{\rm jet\ ch} <$ 30 GeV/$c$ where the QCD emissions are sensitive to mass effects. In $pp$ collisions, heavy flavor jets have less momentum-balanced splittings than inclusive jets and the larger quark mass is, the less momentum-balanced splittings are. B$^0$-tagged jets distribute at lager $R_g$ than both D$^0$-tagged and inclusive jets, while D$^0$-tagged jets distribute at smaller $R_g$ than inclusive jets. That can be explained by the competition between parton mass effects and flavour effects on splitting-angle distributions. In $A$+$A$ collisions, jet quenching effects further suppress the momentum-balanced splittings and enhance the large-angle splittings. Heavy flavor jets suffer more $z_g$ and less $R_g$ modifications due to jet-medium interactions. The mass hierarchy in $z_g$ of inclusive, D$^0$-tagged, B$^0$-tagged jets and competition between mass effects and Casimir colour factors in $R_g$ can also be observed in PbPb collisions.

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