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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 consider the quantum kinetic-theory description for interacting massive spin-half fermions using the Wigner function formalism. We derive a general kinetic theory description assuming that the spin effects appear at the classical and…

High Energy Physics - Theory · Physics 2023-09-11 Arpan Das , Wojciech Florkowski , Avdhesh Kumar , Radoslaw Ryblewski , Rajeev Singh

Four formulations of perfect spin hydrodynamics for spin-1/2 particles, distinguished by their treatment of spin (classical vs. quantum) and by the underlying particle statistics (Boltzmann vs. Fermi-Dirac), are analyzed and shown to…

High Energy Physics - Phenomenology · Physics 2025-11-25 Samapan Bhadury , Zbigniew Drogosz , Wojciech Florkowski , Sudip Kumar Kar , Valeriya Mykhaylova

We present an extension of relativistic single-particle distribution function for weakly interacting particles at local thermodynamical equilibrium including spin degrees of freedom, for massive spin 1/2 particles. We infer, on the basis of…

Nuclear Theory · Physics 2015-06-15 F. Becattini , V. Chandra , L. Del Zanna , E. Grossi

The concept of the Wigner function is used to construct a semi-classical kinetic theory describing the evolution of the axial-current phase-space density of spin-1/2 particles in the relaxation time approximation. The resulting approach can…

High Energy Physics - Phenomenology · Physics 2021-02-01 Samapan Bhadury , Wojciech Florkowski , Amaresh Jaiswal , Avdhesh Kumar , Radoslaw Ryblewski

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 compare two recently developed frameworks of perfect spin hydrodynamics for spin-$1/2$ particles, based respectively on classical kinetic theory and the Wigner function. We show that the conserved currents in both approaches have the…

High Energy Physics - Phenomenology · Physics 2026-01-30 Zbigniew Drogosz

Starting from the Pauli Hamiltonian operator, we derive a scalar quantum kinetic equations for spin-1/2 systems. Here the regular Wigner two-state matrix is replaced by a scalar distribution function in extended phase space. Apart from…

Quantum Gases · Physics 2010-04-21 Jens Zamanian , Mattias Marklund , Gert Brodin

The formulation of relativistic hydrodynamics for massive particles with spin 1/2 is shortly reviewed. The proposed framework is based on the Wigner function treated in a semi-classical approximation or, alternatively, on a classical…

Nuclear Theory · Physics 2020-12-17 Wojciech Florkowski

We give a brief overview of the kinetic theory for spin-1/2 fermions in Wigner function formulism. The chiral and spin kinetic equations can be derived from equations for Wigner functions. A general Wigner function has 16 components which…

High Energy Physics - Phenomenology · Physics 2021-02-03 Jian-Hua Gao , Zuo-Tang Liang , Qun Wang

In this paper we derive a fully relativistic kinetic theory for spin-1/2 particles and its coupling to Maxwell's equations, valid in the long scale-length limit, where the fields vary on a scale much longer than the localization of the…

Plasma Physics · Physics 2017-08-30 Robin Ekman , Felipe A. Asenjo , Jens Zamanian

Recently advocated expressions for the phase-space dependent spin-1/2 density matrices of particles and antiparticles are analyzed in detail and reduced to the forms linear in the Dirac spin operator. This allows for a natural determination…

We review the calculation of polarization in a relativistic fluid within the framework of statistical quantum field theory. We derive the expressions of the spin density matrix and the mean spin vector both for a single quantum relativistic…

High Energy Physics - Theory · Physics 2023-07-31 F. Becattini

The new numerical version of the Wigner approach to quantum mechanics for treatment thermodynamic properties of strongly coupled systems of particles has been developed for extreme conditions, when analytical approximations obtained in…

Plasma Physics · Physics 2018-01-17 A. S. Larkin , V. S. Filinov , V. E. Fortov

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

A power expansion scheme is set up to determine the Wigner function that satisfies the quantum kinetic equation for spin-1/2 charged fermions in a background electromagnetic field. Vector and axial-vector current induced by magnetic field…

High Energy Physics - Phenomenology · Physics 2012-12-27 Jian-Hua Gao , Zuo-Tang Liang , Shi Pu , Qun Wang , Xin-Nian Wang

The Weyl-Wigner representation of quantum mechanics allows one to map the density operator in a function in phase space - the Wigner function - which acts like a probability distribution. In the context of statistical mechanics, this…

Quantum Physics · Physics 2023-08-31 Marcos Gil de Oliveira , Alfredo Miguel Ozorio de Almeida

We outline the hybrid framework of spin hydrodynamics, combining classical kinetic theory with the Israel-Stewart method of introducing dissipation. We obtain the local equilibrium expressions for the baryon current, the energy-momentum…

High Energy Physics - Phenomenology · Physics 2025-08-18 Zbigniew Drogosz

The Dirac field, spin 1/2 particles, is investigated in phase space. The Dirac propagator is defined. The Thermo Field Dynamics (TFD) formalism is used to introduce finite temperature. The energy-momentum tensor is calculated at finite…

High Energy Physics - Theory · Physics 2020-05-26 R. G. G. Amorim , S. C. Ulhoa , J. S da Cruz Filho , A. F. Santos , F. C. Khanna

We derive a Cooper-Frye type spin polarization formula for Dirac fermions at local thermal equilibrium described by a grand canonical ensemble specified by temperature, fluid velocity, chemical potential, and spin potential. We discuss the…

Nuclear Theory · Physics 2022-06-06 Yu-Chen Liu , Xu-Guang Huang