HHIQCD2024

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

Nov 7, 2024, 5:30 PM

30m

Panasonic Auditorium, Yukawa Hall (YITP)

4th week (Nuclear matter under extreme conditions) 1-day workshop (4th week)

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 neutron star (NS) matter by constructing a parity doublet model 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.

Presentation materials

Ppt fot HHIQCD 2024 (07112024) Kong Yuk Kei.pdf