Heavy quarkonium spin transport in a hot medium
Abstract
We investigate the in-medium spin transport of heavy quarkonium using an open-quantum-system approach based on potential nonrelativistic QCD. We express the heavy quarkonium dilepton decay angular distribution in terms of late-time quarkonium spin-dependent distribution functions. Working in the quantum-optical regime, where the inverse quarkonium size is much larger than the binding energy and the binding energy is comparable to or larger than the medium temperature T, we derive a spin-dependent quantum master equation incorporating both dissociation and regeneration, followed by the corresponding projected semiclassical Boltzmann equations. At leading order in the coupling, we retain the recoil corrections of relative order T/M that contribute to the leading spin-dependent collision kernel. Here M denotes the heavy-quark mass. At zeroth order in fluid gradients, we show that the relative motion between quarkonium and the medium supplies the leading anisotropy, while spin-chromomagnetic and spin-orbit interactions both contribute to the leading nonzero spin-alignment kernel. As an exploratory phenomenological application, we also estimate the medium-induced polarization parameter λθ of bottomonium Υ(1S) using a simplified rate equation with background density matrices obtained from the Lindblad equation using QTraj. Within this simplified treatment, the resulting medium-induced polarization is found to be very small while a naive rescaling for charmonium can qualitatively describe the polarization of charmonium.
Related
- Spin transport in intermediate-energy heavy-ion collisions
- Application of Grassmannian techniques and Kubo formula to the transport of fermions in a two-dimensional frustrated spin medium
- Observables in exclusive heavy quarkonium electroproduction at NLO and prospects for the EIC
- Relativistic corrections to heavy quarkonium +γ production at super Z factory
- Complex chromoelectric polarizability of a heavy-quarkonium resonance: pole response and channel-resolved effective-theory representation
BibTeX
@misc{brambilla2026heavy,
title = {{Heavy quarkonium spin transport in a hot medium}},
author = {Nora Brambilla and Shuo Fang and Tom Magorsch and Panayiotis Panayiotou},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.06707},
eprint = {2611.06707},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.06707},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Heavy quarkonium spin transport in a hot medium
AU - Nora Brambilla
AU - Shuo Fang
AU - Tom Magorsch
AU - Panayiotis Panayiotou
PY - 2026
DA - 2026/11/04
PB - arXiv
DO - 10.48550/arxiv.2611.06707
UR - https://arxiv.org/abs/2611.06707
AB - We investigate the in-medium spin transport of heavy quarkonium using an open-quantum-system approach based on potential nonrelativistic QCD. We express the heavy quarkonium dilepton decay angular distribution in terms of late-time quarkonium spin-dependent distribution functions. Working in the quantum-optical regime, where the inverse quarkonium size is much larger than the binding energy and the binding energy is comparable to or larger than the medium temperature T, we derive a spin-dependent quantum master equation incorporating both dissociation and regeneration, followed by the corresponding projected semiclassical Boltzmann equations. At leading order in the coupling, we retain the recoil corrections of relative order T/M that contribute to the leading spin-dependent collision kernel. Here M denotes the heavy-quark mass. At zeroth order in fluid gradients, we show that the relative motion between quarkonium and the medium supplies the leading anisotropy, while spin-chromomagnetic and spin-orbit interactions both contribute to the leading nonzero spin-alignment kernel. As an exploratory phenomenological application, we also estimate the medium-induced polarization parameter λ_θ of bottomonium Υ(1S) using a simplified rate equation with background density matrices obtained from the Lindblad equation using QTraj. Within this simplified treatment, the resulting medium-induced polarization is found to be very small while a naive rescaling for charmonium can qualitatively describe the polarization of charmonium.
ER -