Role of $Σ^*(1385)$ on $Λ$ hyperon polarization in relativistic heavy ion collisions
Fuente:
arXiv
Saved in:
| Main Authors: | , , |
|---|---|
| Format: | Preprint |
| Published: |
2025
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866915733458386944 |
|---|---|
| author | Sung, Haesom Ko, Che Ming Lee, Su Houng |
| author_facet | Sung, Haesom Ko, Che Ming Lee, Su Houng |
| contents | The effect of $Σ^*(1385)$ baryon resonance on the time evolution of the $Λ$ hyperon polarization in hadronic matter is studied using a kinetic approach. This approach explicitly includes the production of the $Σ^*$ resonance from the $Λ-π$ and $Σ(1192)-π$ scatterings as well as its decay into $Λ+π$ or $Σ+π$. The resulting coupled kinetic equations governing the time evolution of $Λ$, $Σ$ and $Σ^*$ numbers and polarizations are solved for Au-Au collisions at $\sqrt{s_{NN}}=7.7$ GeV and 20-50\% centrality, using initial values determined by thermal yields and the thermal vorticity at chemical freeze-out temperature. As the hadronic matter expands and cools, the $Λ$ polarization is found to increase slightly during early times and then decreases very slowly afterwards, while the $Σ$ polarization remains nearly constant and the $Σ^*$ polarization continuously decreases. Including feed-down contributions to the $Λ$ polarization from the decays of partially polarized $Σ^0$, $Σ^*$, and $Ξ(1322)$ hyperons, where the $Ξ$ polarization is obtained by solving coupled kinetic equations for the $Ξ$ and $Ξ^*(1532)$ system, the resulting $Λ$ polarization becomes smaller and decreases over time. In both cases, however, the time variation of the $Λ$ polarization is sufficiently small to support the assumption of an early freeze-out of $Λ$ spin degree of freedom in relativistic heavy ion collisions. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_23238 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Role of $Σ^*(1385)$ on $Λ$ hyperon polarization in relativistic heavy ion collisions Sung, Haesom Ko, Che Ming Lee, Su Houng Nuclear Theory The effect of $Σ^*(1385)$ baryon resonance on the time evolution of the $Λ$ hyperon polarization in hadronic matter is studied using a kinetic approach. This approach explicitly includes the production of the $Σ^*$ resonance from the $Λ-π$ and $Σ(1192)-π$ scatterings as well as its decay into $Λ+π$ or $Σ+π$. The resulting coupled kinetic equations governing the time evolution of $Λ$, $Σ$ and $Σ^*$ numbers and polarizations are solved for Au-Au collisions at $\sqrt{s_{NN}}=7.7$ GeV and 20-50\% centrality, using initial values determined by thermal yields and the thermal vorticity at chemical freeze-out temperature. As the hadronic matter expands and cools, the $Λ$ polarization is found to increase slightly during early times and then decreases very slowly afterwards, while the $Σ$ polarization remains nearly constant and the $Σ^*$ polarization continuously decreases. Including feed-down contributions to the $Λ$ polarization from the decays of partially polarized $Σ^0$, $Σ^*$, and $Ξ(1322)$ hyperons, where the $Ξ$ polarization is obtained by solving coupled kinetic equations for the $Ξ$ and $Ξ^*(1532)$ system, the resulting $Λ$ polarization becomes smaller and decreases over time. In both cases, however, the time variation of the $Λ$ polarization is sufficiently small to support the assumption of an early freeze-out of $Λ$ spin degree of freedom in relativistic heavy ion collisions. |
| title | Role of $Σ^*(1385)$ on $Λ$ hyperon polarization in relativistic heavy ion collisions |
| topic | Nuclear Theory |
| url | https://arxiv.org/abs/2507.23238 |