Bulk viscosity in kaon-condensed color-flavor locked quark matter

Abstract

Color-flavor locked (CFL) quark matter at high densities is a color superconductor, which spontaneously breaks baryon number and chiral symmetry. Its low-energy thermodynamic and transport properties are therefore dominated by the H (superfluid) boson, and the octet of pseudoscalar pseudo-Goldstone bosons of which the neutral kaon is the lightest. We study the CFL-K^0 phase, in which the stress induced by the strange quark mass causes the kaons to condense, and there is an additional ultra-light "K^0" Goldstone boson arising from the spontaneous breaking of isospin. We compute the bulk viscosity of matter in the CFL-K^0 phase, which arises from the beta-equilibration processes K^0<->H+H and K^0+H<->H. We find that the bulk viscosity varies as T^7, unlike the CFL phase where it is exponentially Boltzmann-suppressed by the kaon's energy gap. However, in the temperature range of relevance for r-mode damping in compact stars, the bulk viscosity in the CFL-K^0 phase turns out to be even smaller than in the uncondensed CFL phase, which already has a bulk viscosity much smaller than all other known color-superconducting quark phases.

23 pages, 8 figures, v2: references added; minor rephrasings in the conclusions; version to appear in J. Phys. G

References in corpus (20)

• A calculation of the bulk viscosity in SU(3) gluodynamics
• Modern compact star observations and the quark matter equation of state
• The rigidity of crystalline color superconducting quark matter
• Bulk viscosity of superfluid neutron stars
• Pion and Kaon Condensation at Finite Temperature and Density
• Testing the Ginzburg-Landau approximation for three-flavor crystalline color superconductivity
• Bulk viscosity of strange quark matter: Urca versus non-leptonic processes
• Bulk viscosity due to kaons in color-flavor-locked quark matter
• Neutrino emission from compact stars and inhomogeneous color superconductivity
• Bulk viscosity in 2SC quark matter
• Bulk viscosity in a cold CFL superfluid
• Bulk viscosity in nuclear and quark matter: A short review
• Color-spin locking in a self-consistent Dyson-Schwinger approach
• Critical temperature for kaon condensation in color-flavor locked quark matter
• Bulk viscosity in kaon condensed matter
• Goldstone boson currents in a kaon condensed CFL phase
• Mass spectrum of diquarks and mesons in the color--flavor locked phase of dense quark matter
• Pseudoscalar Goldstone bosons in the color-flavor locked phase at moderate densities
• The Crystallography of Strange Quark Matter
• A diagrammatic derivation of the meson effective masses in the neutral color-flavor-locked phase of Quantum Chromodynamics

Cited by in corpus (2)

• Mutual friction in a cold color flavor locked superfluid and r-mode instabilities in compact stars
• Pseudoscalar bosonic excitations in the color-flavor locked phase at moderate densities