http://arxiv.org/abs/2007.10615
Phases of nuclear matter are crucial in determination of the physical properties of neutron stars~(NS). In the core of NS, it is possible that the density and pressure become so large that the nuclear matter undergoes phase transition into a deconfined phase, consisting of quarks and gluons and their colour bound states. Even though the quark-gluon plasma has been observed in ultra-relativistic heavy-ion collisions\cite{Gyulassy, Andronic}, it is still unclear whether exotic quark matter exists inside neutron stars. Recently the result from the combination of various perturbative theoretical calculations with astronomical observations\cite{Demorest, Antoniadis} shows that (exotic) quark matter could exist inside the cores of neutron stars above 2.0 solar masses ($M_{\odot}$)~\cite{Annala:2019puf} However, due to the nonperturbative characteristic of interactions between quarks and gluons in the deconfined phase, perturbative QCD~(pQCD) has limitation due to the possibly large coupling of the quark-gluon soup in such dense environment. We revisit the holographic model in Ref.~\cite{bch, bhp} and implement the equation of states~(EoS) of multiquark nuclear matter interpolating from the high-density pQCD EoS and matching with the nuclear EoS known at low densities. It is found that the equations of the states of multiquark nuclear phase provide the missing link between the constraints in both high and low energy density regions and give the mass of NS with multiquark core within the observational range. This shows evidence for the exotic multiquark core inside massive neutron stars. The NS with multiquark core at the maximum mass could have masses in the range $2.0-2.8 M_{\odot}$ and radii $10-14$ km.
S. Pinkanjanarod and P. Burikham
Wed, 22 Jul 20
-431/67
Comments: 8 pages, 6 figures
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