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Main Authors: Zhang, Zhong-Hua, Huang, Xu-Guang, Becattini, Francesco, Sheng, Xin-Li
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2412.19416
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author Zhang, Zhong-Hua
Huang, Xu-Guang
Becattini, Francesco
Sheng, Xin-Li
author_facet Zhang, Zhong-Hua
Huang, Xu-Guang
Becattini, Francesco
Sheng, Xin-Li
contents We derive expressions for the vector and tensor components of the spin polarization of massive vector bosons at local thermodynamic equilibrium up to second order in the space-time gradients of the thermodynamic fields pertaining to the canonical stress-energy tensor and spin tensor of the free Proca field. A set of Feynman rules is devised to calculate the Wigner function and the matrix-valued spin-dependent distribution (MVSD) functions order by order in space-time gradients. Due to constraints imposed by time-reversal symmetry, the leading contribution to spin alignment - defined as the 00-component of the tensor polarization - arises from second-order terms in MVSD, for which we provide an analytic formula. We discuss the physical meaning of different contributions to vector and tensor polarization. These formulae provide a prediction of a contribution to the spin alignment which can be compared with the observations in relativistic heavy-ion collisions.
format Preprint
id arxiv_https___arxiv_org_abs_2412_19416
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Vector and Tensor Spin Polarization for Vector Bosons at Local Equilibrium
Zhang, Zhong-Hua
Huang, Xu-Guang
Becattini, Francesco
Sheng, Xin-Li
High Energy Physics - Phenomenology
Nuclear Theory
We derive expressions for the vector and tensor components of the spin polarization of massive vector bosons at local thermodynamic equilibrium up to second order in the space-time gradients of the thermodynamic fields pertaining to the canonical stress-energy tensor and spin tensor of the free Proca field. A set of Feynman rules is devised to calculate the Wigner function and the matrix-valued spin-dependent distribution (MVSD) functions order by order in space-time gradients. Due to constraints imposed by time-reversal symmetry, the leading contribution to spin alignment - defined as the 00-component of the tensor polarization - arises from second-order terms in MVSD, for which we provide an analytic formula. We discuss the physical meaning of different contributions to vector and tensor polarization. These formulae provide a prediction of a contribution to the spin alignment which can be compared with the observations in relativistic heavy-ion collisions.
title Vector and Tensor Spin Polarization for Vector Bosons at Local Equilibrium
topic High Energy Physics - Phenomenology
Nuclear Theory
url https://arxiv.org/abs/2412.19416