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Dark matter with chiral symmetry admixed with hadronic matterin compact stars
Si-Na Wei, Zhao-Qing Feng
Published: , doi: 10.1088/1674-1137/ac3d28
Using the two-fluid Tolman-Oppenheimer-Volkoff equation, the properties of dark matter (DM) admixed neutron stars (DANSs) have been investigated. In contrast to previous studies, we find that an increase in the maximum mass and a decrease in the radius of 1.4 $ M_\odot $ NSs can occur simultaneously in DANSs. This stems from the ability of the equation of state (EOS) for DM to be very soft at low density but very stiff at high density. It is well known that the IU-FSU and XS models are unable to produce a neutron star (NS) with a maximum mass greater than 2.0 $ M_\odot $. However, by considering the IU-FSU and XS models for DANSs, there are interactions with DM that can produce a maximum mass greater than 2.0 $ M_\odot $ and a radius of 1.4 $ M_\odot $ NSs below 13.7 km. When considering a DANS, the difference between DM with chiral symmetry (DMC) and DM with meson exchange (DMM) becomes obvious when the central energy density of DM is greater than that of nuclear matter (NM). In this case, the DMC model with a DM mass of 1000 MeV can still produce a maximum mass greater than 2.0 $ M_\odot $ and a radius of a 1.4 $ M_\odot $ NS below 13.7 km. Additionally, although the maximum mass of the DANS using the DMM model is greater than 2.0 $ M_\odot $, the radius of a 1.4 $ M_\odot $ NS can surpass 13.7 km. In the two-fluid system, the maximum mass of a DANS can be larger than 3.0 $ M_\odot $. Consequently, the dimensionless tidal deformability $ \Lambda_{CP} $ of a DANS with 1.4 $ M_\odot $, which increases with increasing maximum mass, may be larger than 800 when the radius of the 1.4 $ M_\odot $ DANS is approximately 13.0 km.
Scalar and Dirac quasinormal modes of scalar-tensor-Gauss-Bonnet black holes
Tong-Zheng Wang, Wei-Liang Qian, Juan Fernando Zapata Zapata, Kai Lin
Published: , doi: 10.1088/1674-1137/ac3d29
This study explores the scalar and Dirac quasinormal modes pertaining to a class of black hole solutions in the scalar-tensor-Gauss-Bonnet theory. The black hole metrics in question are novel analytic solutions recently derived in the extended version of the theory, which effectively follows at the level of the action of string theory. Owing to the existence of a nonlinear electromagnetic field, the black hole solution possesses a nonvanishing magnetic charge. In particular, the metric is capable of describing black holes with distinct characteristics by assuming different values of the ADM mass and the magnetic charge. This study investigates the scalar and Dirac perturbations in these black hole spacetimes; in particular, we focus on two different types of solutions, based on distinct horizon structures. The properties of the complex frequencies of the obtained dissipative oscillations are investigated, and the stability of the metric is subsequently addressed. We also elaborate on the possible implications of this study.
Pattern for flavor-dependent quark-antiquark interaction
Muyang Chen, Lei Chang
A flavor-dependent kernel is constructed based on the rainbow-ladder truncation of the Dyson-Schwinger and Bethe-Salpeter equation approach of quantum chromodynamics. The quark-antiquark interaction is composed of a flavor-dependent infrared part and a flavor-independent ultraviolet part. Our model gives a successful and unified description of the light, heavy, and heavy-light ground pseudoscalar and vector mesons. For the first time, our model shows that the infrared-enhanced quark-antiquark interaction is stronger and wider for lighter quarks.