Quantum spin dynamics of heavy quarks and polarization observables in relativistic heavy-ion collisions

Fuente: arXiv
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Main Authors: Jaiswal, Sunil, Dey, Sourav, Jaiswal, Amaresh
Format: Preprint
Published: 2026
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author Jaiswal, Sunil
Dey, Sourav
Jaiswal, Amaresh
author_facet Jaiswal, Sunil
Dey, Sourav
Jaiswal, Amaresh
contents We develop a quantum spin-density-matrix framework for heavy-quark spin dynamics in relativistic heavy-ion collisions. Starting from an initial polarization induced along the magnetic-field direction, we derive the evolution equation for spin polarization within this framework and obtain analytic solutions. The evolved polarization is connected to open heavy-flavor observables via a fragmentation-based hadronization prescription. For vector mesons, the spin-alignment parameter $ρ_{00}$ is constructed by coupling the heavy-quark spin to that of the light antiquark produced during fragmentation. We confront our results with recent ALICE measurements of prompt $D^{*+}$ spin alignment in Pb--Pb collisions at $\sqrt{s_{\rm NN}}=5.02~{\rm TeV}$ and extract an effective depolarization strength that determines the spin-relaxation time scale. Using this fitted parameter, we provide benchmark estimates for $Λ_c^+$ and $\barΛ_c^-$ polarization, up to an overall spin-transfer normalization. We further estimate the recently proposed elliptic polarization harmonic arising from path-length-dependent depolarization in an anisotropic fireball.
format Preprint
id arxiv_https___arxiv_org_abs_2605_06461
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quantum spin dynamics of heavy quarks and polarization observables in relativistic heavy-ion collisions
Jaiswal, Sunil
Dey, Sourav
Jaiswal, Amaresh
High Energy Physics - Phenomenology
Nuclear Theory
We develop a quantum spin-density-matrix framework for heavy-quark spin dynamics in relativistic heavy-ion collisions. Starting from an initial polarization induced along the magnetic-field direction, we derive the evolution equation for spin polarization within this framework and obtain analytic solutions. The evolved polarization is connected to open heavy-flavor observables via a fragmentation-based hadronization prescription. For vector mesons, the spin-alignment parameter $ρ_{00}$ is constructed by coupling the heavy-quark spin to that of the light antiquark produced during fragmentation. We confront our results with recent ALICE measurements of prompt $D^{*+}$ spin alignment in Pb--Pb collisions at $\sqrt{s_{\rm NN}}=5.02~{\rm TeV}$ and extract an effective depolarization strength that determines the spin-relaxation time scale. Using this fitted parameter, we provide benchmark estimates for $Λ_c^+$ and $\barΛ_c^-$ polarization, up to an overall spin-transfer normalization. We further estimate the recently proposed elliptic polarization harmonic arising from path-length-dependent depolarization in an anisotropic fireball.
title Quantum spin dynamics of heavy quarks and polarization observables in relativistic heavy-ion collisions
topic High Energy Physics - Phenomenology
Nuclear Theory
url https://arxiv.org/abs/2605.06461