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Related papers: Vector and Tensor Spin Polarization for Vector Bos…

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We investigate the spin alignment of vector mesons arising from locally polarized quarks and anti-quarks (local spin alignment) in heavy-ion collisions. We find that $\rho_{00}\neq 1/3$ does not necessarily signal the global polarization of…

Nuclear Theory · Physics 2021-04-30 Xiao-Liang Xia , Hui Li , Xu-Guang Huang , Huan Zhong Huang

We construct a matrix-valued spin-dependent distribution function (MVSD) for massive spin-1/2 fermions and study its properties under Lorentz transformations. Such transformations result in a Wigner rotation in spin space and in a…

Nuclear Theory · Physics 2022-12-21 Xin-Li Sheng , Qun Wang , Dirk H. Rischke

Using the same method as that used in $e^+e^-$ annihilation and lepton-nucleon deep-inelastic scattering, we calculate the spin alignment of vector mesons with high transverse momenta in high energy $pp$ collisions with one longitudinally…

High Energy Physics - Phenomenology · Physics 2009-11-10 Qing-hua Xu , Zuo-tang Liang

We show that the inclusion of a recently found additional term of the spin polarization vector at local equilibrium which is linear in the symmetrized gradients of the velocity field, and the assumption of hadron production at constant…

Nuclear Theory · Physics 2022-01-12 F. Becattini , M. Buzzegoli , G. Inghirami , I. Karpenko , A. Palermo

We analyze algebraic structure of a relativistic semi-classical Wigner function of particles with spin 1/2 and show that it consistently includes information about the spin density matrix both in two-dimensional spin and four-dimensional…

Nuclear Theory · Physics 2020-06-24 Wojciech Florkowski , Avdhesh Kumar , Radoslaw Ryblewski

Based on the Wigner function in local equilibrium, we derive hydrodynamical quantities for a system of polarized spin-1/2 particles: the particle number current density, the energy-momentum tensor, the spin tensor, and the dipole moment…

High Energy Physics - Theory · Physics 2021-12-22 Hao-Hao Peng , Jun-Jie Zhang , Xin-Li Sheng , Qun Wang

We calculate the Wigner function for charged spin-1 particles in inhomogeneous classical electromagnetic fields, going to first order in a power series in $\hbar$. The Boltzmann equation for the scalar distribution function obtained from…

Nuclear Theory · Physics 2022-07-29 David Wagner , Nora Weickgenannt , Enrico Speranza

We present an upgraded formula for Wigner function and spin polarization of fermions emitted by a relativistic fluid at local thermodynamic equilibrium at the decoupling which improves the one obtained in refs. [1, 2] and used in numerical…

Nuclear Theory · Physics 2026-01-23 Xin-Li Sheng , Francesco Becattini , Daniele Roselli

We propose a novel mechanism that the spin alignment of vector meson $\phi$ and $K^{*0}$ in most central heavy ion collisions is induced by intrinsic QCD dynamics without external vortical/ magnetic fields. The local spin density…

High Energy Physics - Phenomenology · Physics 2024-10-21 Kun Xu , Mei Huang

We study the longitudinal spin polarization of a relativistic fluid of massive spin-1/2 particles undergoing a boost-invariant expansion in the longitudinal direction and rotating in the transverse plane. We express the polarization vector…

Nuclear Theory · Physics 2025-03-18 Nora Weickgenannt , Jean-Paul Blaizot

A recently proposed Boltzmann local equilibrium Wigner function for massive spin-1/2 particles is generalized to the case of Fermi-Dirac statistics. The resulting formula ensures the correct normalization of the mean polarization vector and…

Quantum Physics · Physics 2025-11-18 Sudip Kumar Kar , Valeriya Mykhaylova

The tensor polarization of particles and nuclei is constant in a coordinate system rotating with the same angular velocity as the spin. In the laboratory frame, it rotates with this angular velocity. The general equation defining the…

High Energy Physics - Phenomenology · Physics 2019-05-01 Alexander J. Silenko

Formal connections between the spin density matrix and the Wigner function for spin-1/2 particles forming a relativistic gas are explored to determine their general structures. They suggest that the commonly used form of the local…

High Energy Physics - Phenomenology · Physics 2025-09-30 Samapan Bhadury , Zbigniew Drogosz , Wojciech Florkowski , Sudip Kumar Kar , Valeriya Mykhaylova

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

We estimate both the polarization of spin $1/2$ baryons and the spin density matrix coefficients of spin $1$ mesons using a thermal model that incorporates vorticity and polarization to describe quarks, along with a coalescence formalism…

High Energy Physics - Phenomenology · Physics 2024-10-23 Kayman J. Gonçalves , Giorgio Torrieri , Radoslaw Ryblewski

Recently introduced equilibrium Wigner functions for spin-one-half particles are used in the semiclassical kinetic equations to study the relation between spin polarization and vorticity. It is found, in particular, that such a framework…

Nuclear Theory · Physics 2019-07-16 Avdhesh Kumar

We revisit the spin effects induced by thermal vorticity by calculating them directly from the spin-dependent distribution functions. For the spin-1/2 particles, we give the polarization up to the first order of thermal vorticity and…

High Energy Physics - Phenomenology · Physics 2023-11-17 Jian-Hua Gao , Shi-Zheng Yang

We present a calculation of the spin polarization of spin-1/2 fermions in a relativistic fluid at local thermodynamic equilibrium at the second order in the gradient expansion, including second-order derivatives. The second-order derivative…

High Energy Physics - Theory · Physics 2025-01-22 Xin-Li Sheng , Francesco Becattini , Xu-Guang Huang , Zhong-Hua Zhang

We calculate and investigate the relativistic correlation function for bipartite systems of spin-1/2 in vector and spin-1 particles in tensor states. We show that the relativistic correlation function, which depends on particles momenta,…

Quantum Physics · Physics 2015-05-20 Paweł Caban , Jakub Rembieliński , Marta Włodarczyk

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