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Register a new userCrossover transition in bag-like models
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We formulate a simple model for a gas of extended hadrons at zero chemical potential by taking inspiration from the compressible bag model. We show that a crossover transition qualitatively similar to lattice QCD can be reproduced by such a system by including some appropriate additional dynamics. Under certain conditions, at high temperature, the system consist of a finite number of infinitely extended bags, which occupy the entire space. In this situation the system behaves as an ideal gas of quarks and gluons.
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We study the hadron-quark phase transition in the interior of neutron stars (NS). For the hadronic sector, we use a microscopic equation of state (EOS) involving nucleons and hyperons derived within the Brueckner-Bethe-Goldstone many-body theory, with realistic two-body and three-body forces. For the description of quark matter, we employ both the MIT bag model with a density dependent bag constant, and the color dielectric model. We calculate the structure of NS interiors with the EOS comprising both phases, and we find that the NS maximum masses are never larger than 1.7 solar masses, no matter the model chosen for describing the pure quark phase.
Within the framework of Dyson--Schwinger equations of QCD, we study the effect of finite volume on the chiral phase transition in a sphere with the MIT boundary condition. We find that the chiral quark condensate $langlebar{psi} psirangle$ and pseudotransition temperature $T_{pc}$ of the crossover decreases as the volume decreases, until there is no chiral crossover transition at last. We find that the system for $R = infty $ fm is indistinguishable from $R=10$ fm and there is a significant decrease in $T_{pc}$ with $R$ as $R<4$ fm. When $R<1.5$ fm, there is no chiral transition in the system.
We formulate a simple model for a gas of extended hadrons at zero chemical potential by taking inspiration from the compressible bag model. We show that a crossover transition qualitatively similar to lattice QCD can be reproduced by such a system by including some appropriate additional dynamics. Under certain conditions, at high temperature, the system consists of a finite number of infinitely extended bags, which occupy the entire space. In this situation the system behaves as an ideal gas of quarks and gluons.
We study the star matter properties for Hybrid equation of state (EoS) by varying the bag constant. We use the Effective-Field-Theory motivated Relativistic Mean-Field model (E-RMF) for hadron phase with recently reported FSUGarnet, G3 and IOPB-I parameter sets. The result of NL3 and NL3${omega rho}$ sets are also shown for comparison. The simple MIT Bag model is applied for the quark phase to construct the hybrid EoS. The hybrid neutron star mass and radius are calculated by varying with $B^{1/4}$ to constrain the $B^{1/4}$ values. It is found that $B^{1/4}$=130-160 MeV is suitable for explaining the quark matter in neutron stars.
Inspired by various astrophysical phenomenons, it was suggested that pulsar-like compact stars may in fact be strangeon stars, comprised entirely of strangeons (quark-clusters with three-light-flavor symmetry) and a small amount of electrons. To examine such possibilities, in this work we propose a linked bag model, which can be adopted for strong condensed matter in both 2-flavoured (nucleons) and 3-flavoured (hyperons, strangeons, etc.) scenarios. The model parameters are calibrated to reproduce the saturation properties of nuclear matter, which are later applied to hyperonic matter and strangeon matter. The obtained energy per baryon of strangeon matter is reduced if we adopt larger quark numbers inside a strangeon, which stiffens the equation of state and consequently increases the maximum mass of strangeon stars. In a large parameter space, the maximum mass and tidal deformability of strangeon stars predicted in the linked bag model are consistent with the current astrophysical constraints. It is found that the maximum mass of strangeon stars can be as large as $sim 2.5M_odot$, while the tidal deformability of a $1.4M_odot$ strangeon star lies in the range of $180lesssim Lambda_{1.4} lesssim 340$. More refined theoretical efforts as well as observational tests to these results are necessary in the future.
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