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Register a new userHeavy-quark effects on cold quark matter and self-bound stars
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Added by
Jos\\'e Carlos Jim\\'enez Apaza
Publication date
2021
fields
Physics
and research's language is
English
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Heavy-quark effects on the equation of state for cold and dense quark matter are obtained from perturbative QCD, yielding observables parametrized only by the renormalization scale. In particular, we investigate the thermodynamics of charm quark matter under the constraints of $beta$ equilibrium and electric charge neutrality in a region of densities where perturbative QCD is, in principle, much more reliable. Finally, we analyze the stability of charm stars, a possible new branch of ultradense, self-bound compact stars, and find that they are unstable under radial oscillations.
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We study the effects of heavy quarks on the equation of state for cold and dense quark matter obtained from perturbative QCD, yielding observables parametrized only by the renormalization scale. We investigate the thermodynamics of charm quark matter under the constraints of $beta$ equilibrium and electric charge neutrality in a region of densities where perturbative QCD is, in principle, much more reliable. We also analyze the stability of charm stars, which might be realized as a new branch of ultradense hybrid compact stars, and find that such quark stars are unstable under radial oscillations.
We use a top-down holographic model for strongly interacting quark matter to study the properties of neutron stars. When the corresponding Equation of State (EoS) is matched with state-of-the-art results for dense nuclear matter, we consistently observe a first order phase transition at densities between two and seven times the nuclear saturation density. Solving the Tolman-Oppenheimer-Volkov equations with the resulting hybrid EoSs, we find maximal stellar masses in the excess of two solar masses, albeit somewhat smaller than those obtained with simple extrapolations of the nuclear matter EoSs. Our calculation predicts that no quark matter exists inside neutron stars.
Some time ago we have derived from the QCD Lagrangian an equation of state (EOS) for the cold quark matter, which can be considered an improved version of the MIT bag model EOS. Compared to the latter, our equation of state reaches higher values of the pressure at comparable baryon densities. This feature is due to perturbative corrections and also to non-perturbative effects. Later we applied this EOS to the study of compact stars, discussing the absolute stability of quark matter and computing the mass-radius relation for self-bound (strange) stars. We found maximum masses of the sequences with more than two solar masses, in agreement with the recent experimental observations. In the present work we include the magnetic field in the equation of state and study how it changes the stability conditions and the mass-radius curves.
Brambilla, Escobedo, Soto, and Vairo have derived an effective description of quarkonium with two parameters; a momentum diffusion term and a real self-energy term. We point out that there is a similar real self-energy term for a single open heavy flavor and that it can be expressed directly in terms of Euclidean electric field correlators along a Polyakov line. This quantity can be directly studied on the lattice without the need for analytical continuation. We show that Minkowski-space calculations of this correlator correspond with the known NLO Euclidean value of the relevant electric field two-point function and that it differs from the real self-energy term for quarkonium.
With the recent dawn of the multi-messenger astronomy era a new window has opened to explore the constituents of matter and their interactions under extreme conditions. One of the pending challenges of modern physics is to probe the microscopic equation of state (EoS) of cold and dense matter via macroscopic neutron star observations such as their masses and radii. Still unanswered issues concern the detailed composition of matter in the core of neutron stars at high pressure and the possible presence of e.g. hyperons or quarks. By means of a non-perturbative functional renormalization group approach the influence of quantum and density fluctuations on the quark matter EoS in $beta$-equilibrium is investigated within two- and three-flavor quark-meson model truncations and compared to results obtained with common mean-field approximations where important fluctuations are usually ignored. We find that they strongly impact the quark matter EoS.
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