NUSYM 2024, XIIth International Symposium on Nuclear Symmetry Energy

Bayesian model averaging for nuclear symmetry energy from effective proton-neutron chemical potential difference of neutron-rich nuclei

12 sept. 2024, 15:00

20m

GANIL Guest House (Caen)

Oral Presentation Combined analysis of nuclear and astrophysics information, Bayesian approach, and machine learning

Orateur

Mengying Qiu (Sun Yat-sen University)

Description

The data-driven Bayesian model averaging is a rigorous statistical approach to combining multiple models for a unified prediction. Compared with the individual model, it provides more reliable information, especially for problems involving apparent model dependence. In this work, within both the non-relativistic Skyrme energy density functional and the nonlinear relativistic mean field model, the effective proton-neutron chemical potential difference $\mathrm{\Delta }{\mu }_{\mathrm{p}\mathrm{n}}^{\ast }$ of neutron-rich nuclei is found to be strongly sensitive to the symmetry energy $E_{\mathrm{s}\mathrm{y}\mathrm{m}}(\rho )$ around $2{\rho }_0/3$, with ${\rho }_0$ being the nuclear saturation density. Given discrepancies on the $\mathrm{\Delta }{\mu }_{\mathrm{p}\mathrm{n}}^{\ast }$--$E_{\mathrm{s}\mathrm{y}\mathrm{m}}(2{\rho }_0/3)$ correlations between the two models, we carry out a Bayesian model averaging analysis based on Gaussian process emulators to extract the symmetry energy around $2{\rho }_0/3$ from the measured $\mathrm{\Delta }{\mu }_{\mathrm{p}\mathrm{n}}^{\ast }$ of 5 doubly magic nuclei ${}^{48}$Ca, ${}^{68}$Ni, ${}^{88}$Sr, ${}^{132}$Sn and ${}^{208}$Pb. Specifically, the $E_{\mathrm{sym}}(2{\rho }_0/3)$ is inferred to be $E_{\mathrm{sym}}(2{\rho }_0/3)={25.6}_{-1.3}^{+1.4}\mathrm{MeV}$ at $1\sigma$ confidence level. The obtained constraints on the $E_{\mathrm{sym}}(\rho )$ around $2{\rho }_0/3$ agree well with microscopic predictions and results from other isovector indicators.

Documents de présentation

Mengying_QIU_20240912_NuSym24.pdf