RARiS 研究会「実験、反応・構造計算、格子QCD で解き明かすハドロン分光 2024」

The Effect of Isovector Scalar Meson on Asymmetric Matter Based on a Parity Doublet Model

Not scheduled

20m

　三神峯ホール (東北大学先端量子ビーム科学研究センター)

Plenary Session

Speaker

Yuk Kei Kong (Nagoya University)

Description

"We study the effect of the isovector-scalar meson $a_0$(980) on the properties of nuclear matter and the asymmetric matter by constructing a parity doublet model (PDM) with including the $a_0$ meson based on the chiral SU(2)${}_L\times$SU(2)${}_R$ symmetry. We also include the $\omega$-$\rho$ mixing contribution to adjust the slope parameter at the saturation. We find that, when the chiral invariant mass of nucleon $m_0$ is smaller than about $800$\,MeV, the existence of $a_0$(980) enlarges the symmetry energy by strengthening the repulsive $\rho$ meson coupling. On the other hand, for large $m_0$ where the Yukawa coupling of $a_0$(980) to nucleon is small, the symmetry energy is reduced by the effect of $\omega$-$\rho$ mixing. We then construct the equation of state (EoS) of a neutron star matter to obtain the mass-radius relation of NS.
We find that, in most choices of $m_0$, the existence of $a_0$(980) stiffens the EoS and makes the radius of NS larger. We then constrain the chiral invariant mass of nucleon from the observational data of NS, and find that $580\text{ MeV}\lesssim m_0\lesssim 860\text{ MeV}$ for $L_0=57.7$ MeV. In addition, we study the effect of $a_0$(980) to the nuclei properties such as binding energy and root-mean-square radius based on the PDM with Relativistic Continuum Hartree Bogoliubov Theory."