arXiv subjects

Zaining Wang

Publications and source records attributed to Zaining Wang.

4 recordsLinked to original sources

arXiv2026

Collision energy and system size dependence of $p_{\mathrm{T}}$-differential radial flow fluctuations $v_{0}(p_{\mathrm{T}})$ at RHIC

We report the first RHIC measurements of $v_{0}(p_\mathrm{T})$ in Au+Au collisions at $\sqrt{s_\mathrm{NN}}=7.7$--$200$ GeV and O+O collisions at $\sqrt{s_\mathrm{NN}}=200$ GeV. The integral fluctuation $v_0$ follows a common $N_{\rm ch}$ dependence in large and small systems, suggesting that the fluctuation magnitude is predominantly controlled by event-by-event fluctuations of the initial transverse size. The normalized response $v_0(p_\mathrm{T})/v_0$ factorizes across centralities and systems, revealing a universal hydrodynamic response $\kappa_0(p_\mathrm{T})/\kappa_0$ largely independent of the fluctuation amplitude. Identified-hadron mass ordering and viscous model comparisons demonstrate sensitivity to bulk viscosity ($\zeta/s$). These results establish $v_0(p_\mathrm{T})$ as a probe of the radial hydrodynamic response, collectivity across large and small collision systems, and QGP transport properties.

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arXiv2026

Nonflow Subtraction Beyond Two-Particle Correlations

Establishing collective flow in small collision systems is crucial for pinning down the minimum conditions for quark-gluon plasma (QGP) formation. In two-particle correlations, nonflow has been subtracted with good control, pushing the reach of flow measurements down to very small particle multiplicities $N$. However, the multi-particle nature of collectivity has not been established in the same $N$ regime, because the residual nonflow surviving the subevent procedure in multi-particle cumulants has never been quantified. We develop a general nonflow subtraction framework for $m$-particle cumulants, built around the approximate $1/N^{m-1}$ scaling of nonflow in the independent-source picture. Correlators containing $v_1$ serve as clean nonflow estimators, since the $p_{\rm T}$-integrated dipolar flow nearly vanishes. Using \HIJING{} as a controlled nonflow-only environment, we test the subtraction for three target observables ($\langle v_2^2\rangle$, $\langle v_2^2\delta p_{\rm T}\rangle$, and $c_2\{4\}$) in O+O and $d$+Au at $\sqrt{s_{\rm NN}} = 5.36$ TeV and 200 GeV. Most of the nonflow is removed, with residual fractions typically within 20--30% when converted to the two-particle level, though the best estimator differs across the three targets. We identify a multiplicity-reweighting correction, previously overlooked in two-particle correlations, that explains the long-standing undersubtraction of the naive $1/N$-scaling method; its impact grows as a power of the correlator order. The framework gives a systematic route to nonflow subtraction beyond two-particle correlations, broadening the class of multi-particle observables accessible to the small-system flow program.

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arXiv2024

Disentangling nuclear structure through multiparticle azimuthal correlations in high-energy isobar collisions

Event-by-event fluctuations in the amplitudes of flow harmonics offer a novel approach to probing the initial-state characteristics in heavy-ion collisions. In this study, we conduct a systematic investigation of correlations among various flow harmonics utilizing multiparticle cumulants in $^{96}$Ru+$^{96}$Ru and $^{96}$Zr+$^{96}$Zr collisions at $\sqrtsnn =$ 200 GeV within the framework of a multiphase transport model. Correlated nuclear density distributions specific to the isobar systems are incorporated to evaluate the sensitivity of selected observables to variations in nuclear deformation and neutron skin thickness. The analysis reveals that multiparticle azimuthal correlations are responsive to these nuclear structure features, predominantly in the most central collision events. Furthermore, the examined correlations exhibit shallow dependence on the assumed shear viscosity values. These findings provide a quantitative evaluation of the extent to which multiparticle flow observables can discern nuclear structure effects in isobar collisions and offer valuable guidance for future detailed dynamical investigations and experimental measurements.

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arXiv2024

Systematic investigation of the nuclear multiple deformations in U+U collisions with A Multi-Phase Transport model

Relativistic heavy ion collisions provide a unique opportunity to study the shape of colliding nuclei, even up to higher-order multiple deformations. In this work, several observables that are sensitive to quadrupole and hexadecapole deformations of Uranium-238 in relativistic U+U collisions have been systematically investigated with A Multi-Phase Transport model. We find that the flow harmonic $v_{2}$, the $v_{2}$ and mean transverse momentum correlation, and the three-particle asymmetry cumulant ${\rm ac}_{2}\{3\}$ are sensitive to nuclear quadrupole deformation, while ${\rm ac}_{2}\{3\}$ and nonlinear response coefficient $\chi_{4,22}$ are sensitive to nuclear hexadecapole deformation. Our results from transport model studies are in qualitative agreement with previous hydrodynamic studies. The results indicate that the uncertainties of the hexadecapole deformation of Uranium on the quadrupole deformation determination can be reduced by the abundance of correlation observables provided by the relativistic heavy ion collisions.

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