Constraint to chiral invariant masses of nucleons from GW170817 in an extended parity doublet model

Abstract

We construct nuclear matter based on an extended parity doublet model including four light nucleons N (939), N (1440), N (1535), and N (1650). We exclude some values of the chiral invariant masses by requiring the saturation properties of normal nuclear matter; saturation density, binding energy, incompressibility, and symmetry energy. We find further constraint to the chiral invariant masses from the tidal deformability determined by the observation of the gravitational waves from neutron star merger GW170817. Our result shows that the chiral invariant masses are larger than about 600 MeV. We also give some predictions on the symmetry energy and the slope parameters in the high density region, which will be measured in future experiments.

Speed of sound and quark confinement inside neutron stars

“…When the chiral symmetry is restored, the masses become degenerate with a common finite mass m ± (σ = 0) = m 0 , which reflects the parity doubling structure of the low-lying baryons. Following the previous studies of the parity-doublet-based models [25][26][27][28][29][37][38][39][40][41][42][43][44][45][46][47], as well as recent lattice QCD results [48,49], we choose a rather large value, m 0 = 700 MeV. The couplings g 1 and g 2 in equation 8can be determined by fixing the fermion masses in the vacuum.…”

Speed of sound and quark confinement inside neutron stars

“…When the chiral symmetry is restored, the masses become degenerate with a common finite mass m ± (σ = 0) = m 0 , which reflects the parity doubling structure of the low-lying baryons. Following the previous studies of the parity-doublet-based models [25,26,27,28,29,37,38,39,40,41,42,43,44,45,46,47], as well as recent lattice QCD results [48,49], we choose a rather large value, m 0 = 700 MeV. The couplings g 1 and g 2 in Eq.…”

Quark-hadron crossover equations of state for neutron stars: constraining the chiral invariant mass in a parity doublet model

“…The previous study in Ref. [24] based on the PDM extrapolates the hadronic equations state to the baryon density n B ∼ 3n 0 (n 0 0.16 fm −3 : nuclear saturation density). However, as emphasized in Refs.…”

“…In Ref. [24], the analyses were further extended to NS matter, the chiral invariant mass is restricted to be m 0 600 MeV by the tidal deformability estimated from the NS merger GW170817 [32][33][34].…”