22 October 2024 Tue 4 pm

I will summarize our recent works in Refs. [1]-[4] in which we studied neutron star property based on the PDM-NJL crossover model.

In the low-density region, we construct an EoS using a hadronic model based on the parity doublet structure with the chiral invariant mass of nucleons. In the high density region, an EoS is obtained in an NJL-type quark model. By interpolating two EoSs with assuming the quark-hadron crossover, we construct a unified EoS for dense matter. We then derive the M-R relation of neutron stars from the unified EoS and compare the result with the observational constraints to obtain an allowed range for the chiral invariant mass.

We also study the effect of the isovector-scalar meson a0(980) on the properties of nuclear matter and  the neutron star matter by extending the parity doublet model to include the a0 meson.

We show that, in most choices of the chiral invariant mass, the existence of a0(980) stiffens the EoS and makes the radius of NS larger.

References:

[1] T. Minamikawa, T. Kojo and M. Harada, Phys. Rev. C  103, 045205 (2021);

[2] T. Minamikawa, T. Kojo and M. Harada, Phys. Rev. C  104, 065201 (2021).

[3] T. Minamikawa, B. Gao, T. Kojo and M. Harada, Symmetry 15, 745 (2023).

[4] Y.-K. Kong, T. Minamikawa and M. Harada, Phys. Rev. C 108, 055206 (2023).

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