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Large orbital angular momentum can be generated in non-central heavy-ion collisions, and part of it is expected to be converted into final particle's polarization due to the spin-orbit coupling. Within the framework of A Multi-Phase…

Nuclear Theory · Physics 2017-12-08 Xiao-Liang Xia , Hui Li , Qun Wang

We revisit the azimuthal angle dependence of the local spin polarization of hyperons in heavy-ion collisions at 200 GeV in the framework of the (3+1)D viscous hydrodynamic model CLVisc. Two different initial conditions are considered in our…

Nuclear Theory · Physics 2019-11-06 Hong-Zhong Wu , Long-Gang Pang , Xu-Guang Huang , Qun Wang

The findings on the spin polarization of $\Lambda$, $\Xi$, and $\Omega$ hyperons and spin alignment of $K^{*0}$, $\phi$, and $D^{*+}$ mesons in relativistic heavy-ion collision experiments at the RHIC and LHC facilities propose the…

High Energy Physics - Phenomenology · Physics 2026-02-17 Bhagyarathi Sahoo , Captain R. Singh , Raghunath Sahoo

We present the exact form of the spin polarization vector and the spin density matrix of massive and massless free particles of any spin and helicity at general global equilibrium in a relativistic fluid with non-vanishing thermal…

Nuclear Theory · Physics 2023-06-16 Andrea Palermo , Francesco Becattini

The polarization of the $\Lambda$ particle offers the unique opportunity to study the hydrodynamic gradients in the Quark-Gluon Plasma formed in heavy-ion collisions. However, the theoretical formula commonly used to calculate polarization…

Nuclear Theory · Physics 2023-12-12 Andrea Palermo

Global polarization of $\Lambda$ and $\bar{\Lambda}$ is calculated based on the axial vortical effect (AVE). Simulations are performed within the model of the three-fluid dynamics. Equations of state with the deconfinement transition result…

Nuclear Theory · Physics 2020-10-21 Yu. B. Ivanov

The system created in ultrarelativistic nuclear collisions is known to behave as an almost ideal liquid. In non-central collisions, due to the large orbital momentum, such a system might be the fluid with the highest vorticity ever created…

Nuclear Theory · Physics 2017-05-16 F. Becattini , I. Karpenko , M. Lisa , I. Upsal , S. Voloshin

Global polarization of $\Lambda$ and $\bar{\Lambda}$ hyperons in Au+Au collisions at collision energies $\sqrt{s_{NN}}=$ 4-40 GeV in the midrapidity region and total polarization, i.e. averaged over all rapidities, are studied within the…

Nuclear Theory · Physics 2019-07-31 Yu. B. Ivanov , V. D. Toneev , A. A. Soldatov

The vorticity is a quantity defined in a relativistic fluid that describes how much a fluid element is rotating and accelerating. By measuring the spin polarization of hadrons, it was found that the quark gluon plasma produced in heavy-ion…

Nuclear Theory · Physics 2024-05-17 M. Buzzegoli

We report our recent study on the global and local polarization of $\Lambda$ hyperons in Au+Au collisions at RHIC-BES energies within the (3+1)-dimensional CLVisc hydrodynamics framework. We present our numerical results for the global…

Nuclear Theory · Physics 2023-12-15 Xiang-Yu Wu , Cong Yi , Guang-You Qin , Shi Pu

The extreme temperatures and energy densities generated by ultra-relativistic collisions between heavy nuclei produce a state of matter with surprising fluid properties. Non-central collisions have angular momentum on the order of…

Nuclear Experiment · Physics 2017-08-29 STAR Collaboration

Global polarization of hyperons induced by the local vorticity of the medium created in heavy-ion collisions at energies 2.3\,GeV$\le\sqrt{s_{NN}}\le$11.5 GeV is calculated in the parton-hadron-string dynamic (PHSD) model. The separation of…

Nuclear Theory · Physics 2025-03-12 V. Voronyuk , E. E. Kolomeitsev , N. S. Tsegelnik

Based on the model of three-fluid dynamics (3FD), the global $\Lambda$ polarization ($P_\Lambda$) is calculated in Au+Au collisions at 3 $\leq\sqrt{s_{NN}}\leq$ 9 GeV, in which high baryon density is achieved. Various contributions to…

Nuclear Theory · Physics 2026-02-27 Yu. B. Ivanov

Polarization has opened a new physics chapter in relativistic heavy-ion collisions. Since the first prediction and experimental observation of global spin polarization, a lot of progress has been made in understanding its features, both at…

Nuclear Theory · Physics 2024-02-08 Francesco Becattini , Matteo Buzzegoli , Takafumi Niida , Shi Pu , Ai-Hong Tang , Qun Wang

In hydrodynamic approach to relativistic heavy ion collisions, hadrons with nonzero spin, produced out of the hydrodynamic medium, can acquire polarization via spin-vorticity thermodynamic coupling mechanism. The hydrodynamical quantity…

Nuclear Theory · Physics 2018-03-14 Iurii Karpenko , Francesco Becattini

Global spin polarization of hyperons is an important observable to probe the vorticity of the quark-gluon plasma produced in heavy-ion collisions. We calculate the global polarizations of $\Lambda$, $\Xi^-$, and $\Omega^-$ in Au+Au…

Nuclear Theory · Physics 2022-03-01 Hui Li , Xiao-Liang Xia , Xu-Guang Huang , Huan Zhong Huang

We calculated the azimuthal angle dependence of the local spin polarization of hyperons in 200 GeV Au+Au and 2.76 TeV Pb+Pb collisions in the framework of the (3+1)D viscous hydrodynamic model CLVisc with AMPT initial conditions encoding…

Nuclear Theory · Physics 2021-02-03 Hong-Zhong Wu , Long-Gang Pang , Xu-Guang Huang , Qun Wang

We have implemented the 3+1 dimensional CLVisc hydrodynamics model with TRENTO-3D initial conditions to investigate the spin polarization of $\Lambda$ hyperons along the beam direction in p+Pb collisions at $\sqrt{s_{NN}} = 8.16$ TeV.…

High Energy Physics - Phenomenology · Physics 2024-09-02 Cong Yi , Xiang-Yu Wu , Jie Zhu , Shi Pu , Guang-You Qin

Motivated by the key role of shear induced polarization in understanding the local spin polarization puzzle of $\Lambda$ hyperons in heavy ion collisions, we perform a complete analysis of spin polarization of massive fermion in a quantum…

High Energy Physics - Phenomenology · Physics 2024-12-02 Ziyue Wang , Shu Lin

We use a thermal model with single freeze-out to determine longitudinal polarization of $\Lambda$ hyperons emitted from a hot and rotating hadronic medium. We consider the top RHIC energies and use the model parameters determined in the…

Nuclear Theory · Physics 2019-12-04 Wojciech Florkowski , Avdhesh Kumar , Radoslaw Ryblewski , Aleksas Mazeliauskas