Bulk viscosity of strange quark matter: Urca versus nonleptonic processes

Sa'd, Basil A.; Shovkovy, Igor; Rischke, Dirk H.

doi:10.1103/physrevd.75.125004

Cited by 57 publications

(52 citation statements)

References 40 publications

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“…From the stronger temperature dependence of the corresponding quark Urca rates it is clear that analogous to the direct hadronic Urca case the semi-leptonic contributions to the viscosity also have a stronger amplitude dependence than the non-leptonic contribution. Therefore, at large amplitudes the mixing between these two channels should be far more pronounced than what has been observed previously in the subthermal case [21]. Similar conclusions hold for the mixing in hadronic matter when the hyperonic channel is included [22].…”

Section: B Csupporting

confidence: 55%

“…(11) the maximum value of the bulk viscosity ζ max is independent of the rate and thereby only slightly changed, but the bulk viscosity of the 2SC quark matter reaches its maximum value at higher amplitudes compared to unpaired quark matter. A similar statement holds for the bulk viscosity of 1SC phases [25,26]. Here the corresponding suppression factor depends on the particular pairing pattern, which may involve only part of the quarks on the Fermi surface, and can be as low as 0.03, thereby enhancing the effect discussed for 2SC pairing.…”

Section: B Cmentioning

confidence: 79%

“…The discussed suprathermal effects should be important for the competition of different weak channels contributing to the viscosity. This has been considered for the non-leptonic and Urca channels in strange quark matter in [21]. From the stronger temperature dependence of the corresponding quark Urca rates it is clear that analogous to the direct hadronic Urca case the semi-leptonic contributions to the viscosity also have a stronger amplitude dependence than the non-leptonic contribution.…”

Section: B Cmentioning

confidence: 99%

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Suprathermal viscosity of dense matter

Alford

Mahmoodifar

Schwenzer

2010

AIP Conference Proceedings

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Abstract. Motivated by the existence of unstable modes of compact stars that eventually grow large, we study the bulk viscosity of dense matter, taking into account non-linear effects arising in the large amplitude regime, where the deviation µ ∆ of the chemical potentials from chemical equilibrium fulfills µ ∆ T . We find that this supra-thermal bulk viscosity can provide a potential mechanism for saturating unstable modes in compact stars since the viscosity is strongly enhanced. Our study confirms previous results on strange quark matter and shows that the suprathermal enhancement is even stronger in the case of hadronic matter. We also comment on the competition of different weak channels and the presence of suprathermal effects in various color superconducting phases of dense quark matter.

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Section: B Csupporting

confidence: 55%

Section: B Cmentioning

confidence: 79%

Section: B Cmentioning

confidence: 99%

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Suprathermal viscosity of dense matter

Alford

Mahmoodifar

Schwenzer

2010

AIP Conference Proceedings

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“…On the other hand the coefficient of bulk viscosity may be as large as 10 30 g cm −1 s −1 due to Urca processes in strange quark matter [57] (see also [58] for a review on bulk viscosity in nuclear and quark matter).…”

Section: Introductionmentioning

confidence: 99%

Nonadiabatic charged spherical gravitational collapse

et al. 2007

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We present a complete set of the equations and matching conditions required for the description of physically meaningful charged, dissipative, spherically symmetric gravitational collapse with shear. Dissipation is described with both free-streaming and diffusion approximations. The effects of viscosity are also taken into account. The roles of different terms in the dynamical equation are analyzed in detail. The dynamical equation is coupled to a causal transport equation in the context of Israel-Stewart theory. The decrease of the inertial mass density of the fluid, by a factor which depends on its internal thermodynamic state, is reobtained, with the viscosity terms included. In accordance with the equivalence principle, the same decrease factor is obtained for the gravitational force term. The effect of the electric charge on the relation between the Weyl tensor and the inhomogeneity of energy density is discussed.2

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“…For bulk viscosity in unpaired quark matter, see Refs. [26,27,28,29,30]. 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 000000000 .…”

mentioning

confidence: 99%

Bulk viscosity in 2SC and CFL quark matter

Alford¹,

Schmitt²

2007

AIP Conference Proceedings

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Abstract. The bulk viscosities of two color-superconducting phases, the color-flavor locked (CFL) phase and the 2SC phase, are computed and compared to the result for unpaired quark matter. In the case of the CFL phase, processes involving kaons and the superfluid mode give the largest contribution to the bulk viscosity since all fermionic modes are gapped. In the case of the 2SC phase, ungapped fermionic modes are present and the process u + d ↔ u + s provides the dominant contribution. In both cases, the bulk viscosity can become larger than that of the unpaired phase for sufficiently large temperatures (T 1 MeV for CFL, T 0.1 MeV for 2SC). Bulk viscosity (as well as shear viscosity) is important for the damping of r-modes in compact stars and thus can potentially be used as an indirect signal for the presence or absence of color-superconducting quark matter.Keywords: Color superconductivity, bulk viscosity PACS: 12.38. Mh,24.85.+p,26.60.+c Color superconductivity in compact stars. -Matter at sufficiently large densities and low temperatures is a color superconductor, which is a degenerate Fermi gas of quarks with a condensate of Cooper pairs near the Fermi surface [1]. At asymptotically large densities, where the quark masses are negligibly small compared to the quark chemical potential µ, three-flavor quark matter is in the color-flavor locked (CFL) state [2]. In this state quarks form Cooper pairs in a particularly symmetric fashion. The gauge group of the strong interactions SU (3) c and the chiral symmetry group SU (3) L × SU (3) R are spontaneously broken down to the group of joint color-flavor rotations SU (3) c+L+R . All quarks participate in pairing, giving rise to energy gaps in all quasifermion modes. Therefore, the lightest degrees of freedom in the CFL phase are Goldstone bosons: the broken chiral symmetry gives rise to an octet, with the lightest modes being the charged and neutral kaons (at not asymptotically large densities, chiral symmetry is an approximate symmetry and the Goldstone modes acquire a small mass). Moreover, the CFL phase is a superfluid, spontaneously breaking baryon number conservation symmetry U (1) B . Hence there is a "superfluid mode" which is exactly massless. Goldstone modes in the CFL phase can be described within effective theories [3,4,5], not unlike conventional chiral perturbation theory of the QCD vacuum. The results given below for the CFL bulk viscosity are computed within these effective theories.While rigorous QCD calculations from first principles can be done at asymptotically large densities, the situation is more complicated at moderate densities. Here we are interested in densities of matter inside a compact star. These densities can be as large as several times nuclear ground state density; however, even then the quark chemical potential is at most of the order of 500 MeV. Therefore, perturbative methods within QCD are not applicable and one has to rely on more phenomenological models. Fur-

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Bulk viscosity of strange quark matter: Urca versus nonleptonic processes

Cited by 57 publications

References 40 publications

Suprathermal viscosity of dense matter

Suprathermal viscosity of dense matter

Nonadiabatic charged spherical gravitational collapse

Bulk viscosity in 2SC and CFL quark matter

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