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| Main Authors: | , , , , |
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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2511.01325 |
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| _version_ | 1866910227252641792 |
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| author | You, Hao-Song Yu, Ting-Lan Han, Sophia Xia, Cheng-Jun Xu, Ren-Xin |
| author_facet | You, Hao-Song Yu, Ting-Lan Han, Sophia Xia, Cheng-Jun Xu, Ren-Xin |
| contents | By combining the ($u$,$d$) I-spin doublets or ($d$,$s$) U-spin doublets, the SU(3) flavor symmetry of light quarks can be decomposed into SU(2)$_I\times$U(1)$_Y$ or SU(2)$_U\times$U(1)$_Q$ subgroups, which have been widely adopted to categorize hadrons and their decay properties. The I-spin counterpart for the interactions among nucleons has been extensively investigated, i.e., the nuclear symmetry energy $E_\mathrm{sym}(n_\mathrm{b})$, which characterizes the variation of binding energy as the neutron to proton ratio in a nuclear system. In this work, we propose U-spin symmetry energy $E_\mathrm{U}(n_\mathrm{b})$ for hyperonic matter to characterize the variation of binding energy with the inclusion of hyperons. In particular, being the lightest hyperon, $Λ$ hyperons are included in dense matter, where the U-spin symmetry energy $E_\mathrm{U}(n_\mathrm{b})$ is fixed according to state-of-the-art constraints from nuclear physics and astrophysical observations using Bayesian inference approach. It is found that $E_\mathrm{U}(n_\mathrm{b})$ is much smaller than that of $E_\mathrm{sym}(n_\mathrm{b})$, indicating much stronger proton-neutron attraction than that of nucleon-hyperon pairs. Consequently, the $Λ$ hyperon potential increases significantly with density and becomes repulsive at high densities. The results indicate that there is more than 50\% probability for the emergence of $Λ$ hyperons in posterior EOSs, which are likely to vanish at densities $n_\mathrm{b} \gtrsim 5\,n_0$. In scenarios where $Λ$ hyperons do emerge, the onset density $n_{\mathrm{b}}^Λ$ is typically within the range of $2\,n_0$--$5\,n_0$, corresponding to neutron stars more massive than $1.0\,\rm{M_\odot}$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_01325 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | U-spin symmetry energy and hyperon puzzle You, Hao-Song Yu, Ting-Lan Han, Sophia Xia, Cheng-Jun Xu, Ren-Xin High Energy Physics - Phenomenology High Energy Astrophysical Phenomena By combining the ($u$,$d$) I-spin doublets or ($d$,$s$) U-spin doublets, the SU(3) flavor symmetry of light quarks can be decomposed into SU(2)$_I\times$U(1)$_Y$ or SU(2)$_U\times$U(1)$_Q$ subgroups, which have been widely adopted to categorize hadrons and their decay properties. The I-spin counterpart for the interactions among nucleons has been extensively investigated, i.e., the nuclear symmetry energy $E_\mathrm{sym}(n_\mathrm{b})$, which characterizes the variation of binding energy as the neutron to proton ratio in a nuclear system. In this work, we propose U-spin symmetry energy $E_\mathrm{U}(n_\mathrm{b})$ for hyperonic matter to characterize the variation of binding energy with the inclusion of hyperons. In particular, being the lightest hyperon, $Λ$ hyperons are included in dense matter, where the U-spin symmetry energy $E_\mathrm{U}(n_\mathrm{b})$ is fixed according to state-of-the-art constraints from nuclear physics and astrophysical observations using Bayesian inference approach. It is found that $E_\mathrm{U}(n_\mathrm{b})$ is much smaller than that of $E_\mathrm{sym}(n_\mathrm{b})$, indicating much stronger proton-neutron attraction than that of nucleon-hyperon pairs. Consequently, the $Λ$ hyperon potential increases significantly with density and becomes repulsive at high densities. The results indicate that there is more than 50\% probability for the emergence of $Λ$ hyperons in posterior EOSs, which are likely to vanish at densities $n_\mathrm{b} \gtrsim 5\,n_0$. In scenarios where $Λ$ hyperons do emerge, the onset density $n_{\mathrm{b}}^Λ$ is typically within the range of $2\,n_0$--$5\,n_0$, corresponding to neutron stars more massive than $1.0\,\rm{M_\odot}$. |
| title | U-spin symmetry energy and hyperon puzzle |
| topic | High Energy Physics - Phenomenology High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2511.01325 |