Cold quark matter with heavy quarks and the stability of charm stars

Jiménez, José C.; Fraga, Eduardo S.

doi:10.1103/physrevd.102.034015

Cited by 9 publications

(5 citation statements)

References 52 publications

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“…However, in many situations of interest, only the three lightest quarks are active. For instance, at high densities the pQCD results are convergent for µ q 0.9 GeV, which is larger than the mass of the strange quark m s ≈ 0.1 GeV, and the charm quark is not yet active at this density [12]. A similar situation exists for temperatures T 0.3 GeV, where m s /(πT ) is small, which approaches the regime of relevance for heavy-ion collisions.…”

Section: Introductionmentioning

confidence: 88%

Cool quark matter with perturbative quark masses

Gorda,

Säppi

2021

Preprint

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In perturbative thermal calculations, introducing nonzero quark masses causes considerable complications. In this article we describe an approximation scheme valid for sufficiently light masses which significantly simplifies the relevant calculations with only a small loss in accuracy. We apply the scheme to Quantum Chromodynamics, with two massless and one massive flavor, obtaining analytic results which are in excellent agreement with numerical non-approximated results. Our results are accurate to O(g 5 ) in the strong coupling parameter g, as long as either the chemical potential µ of the quark species with nonzero mass m satisfies m = O(gµ) or if the temperature T satisfies m = O(gT ). We find that these conditions are always satisfied for the three lightest quarks for the values of µ, T where Quantum Chromodynamics is perturbatively convergent.

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Section: Introductionmentioning

confidence: 88%

Cool quark matter with perturbative quark masses

Gorda,

Säppi

2021

Preprint

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“…which corresponds to a sum of the hard gluon term, the soft gluon term, the quark term, which includes the AMM term, and the magnetic field term, where the total quark pressure can be found by summing each flavor for u, d and s quarks-quarks heavier than the s quark-giving rise to radial oscillation instabilities that are not included in the sum [28]; for an analysis of charm star stability, see [87,88]. Here, the baryon number density is n B = (n u + n d + n s )/3, and the nuclear number density is n 0 = 0.17 fm −3 .…”

Section: Qcd-motivated Eosmentioning

confidence: 99%

Cold Quark–Gluon Plasma EOS Applied to a Magnetically Deformed Quark Star with an Anomalous Magnetic Moment

Andrew

Steinfelds

Andrew³

2022

Universe

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We consider a QCD cold-plasma-motivated Equation of State (EOS) to examine the impact of an Anomalous Magnetic Moment (AMM) coupling and small shape deformations on the static oblate and prolate core shapes of quark stars. Using the Fogaça QCD-motivated EOS, which shifts from the high-temperature, low-chemical-potential quark–gluon plasma environment to the low-temperature, high-chemical-potential quark stellar core environment, we consider the impact of an AMM coupling with a metric-induced shape deformation parameter in the Tolman–Oppenheimer–Volkov (TOV) equations. The AMM coupling includes a phenomenological scaling that accounts for the weak and strong field characteristics in dense matter. The EOS is developed using a hard gluon and soft gluon decomposition of the gluon field tensor and using a mean-field effective mass for the gluons. The AMM is considered using the Dirac spin tensor coupled to the EM field tensor with quark-flavor-based magnetic moments. The shape parameter is introduced in a metric ansatz that represents oblate and prolate static stellar cores for modified TOV equations. These equations are numerically solved for the final mass and radius states, representing the core collapse of a massive star with a phase transition leading to an unbound quark–gluon plasma. We find that the combined shape parameter and AMM effects can alter the coupled EOS–TOV equations, resulting in an increase in the final mass and a decrease in the final equatorial radius without collapsing the core into a black hole and without violating causality constraints; we find maximum mass values in the range 1.6 Mʘ < M < 2.5 Mʘ. These states are consistent with some astrophysical, high-mass magnetar/pulsar and gravity wave systems and may provide evidence for a core that has undergone a quark–gluon phase transition such as PSR 0943 + 10 and the secondary from the GW 190814 event.

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“…Taken from Ref. [14]. approximations in the inequalities come from noticing that before the threshold point the electron chemical potential takes its lowest value compared to the strange one, thus allowing us to make the approximation µ c ≈ µ s .…”

Section: Charm Matter Thermodynamicsmentioning

confidence: 99%

“…The case X = 5 is shown only to verify how the EoS depends on X when including one additional heavy flavor. Taken from Ref [14]…”

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confidence: 99%

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Heavy-quark effects on cold quark matter and self-bound stars

Jiménez

Fraga²

2022

EPJ Web Conf.

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The 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 β 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, which might be realized as a new branch of ultradense hybrid compact stars, and find that such self-bound stars are unstable under radial oscillations.

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Cold quark matter with heavy quarks and the stability of charm stars

Cited by 9 publications

References 52 publications

Cool quark matter with perturbative quark masses

Cool quark matter with perturbative quark masses

Cold Quark–Gluon Plasma EOS Applied to a Magnetically Deformed Quark Star with an Anomalous Magnetic Moment

Heavy-quark effects on cold quark matter and self-bound stars

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