Article

# Nucleation of antikaon condensed matter in proto neutron stars

08/2011; DOI: 10.1063/1.3700566

Source: arXiv

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**ABSTRACT:**We study the transition from npe-type nuclear matter (consisting of neutrons, protons, and electrons) to matter containing strangeness, using a Walecka-type model predicting a first-order kaon-condensate phase transition. We examine the free energy of droplets of K-matter as the density, temperature, and neutrino fraction are varied. Langer nucleation rate theory is then used to approximate the rate at which critical droplets of the new phase are produced by thermal fluctuations, thus giving an estimate of the time required for the new (mixed) phase to appear at various densities and various times in the cooling history of the proto-neutron star. We also discuss the famous difficulty of "simultaneous weak interactions" which we connect to the literature on non-topological solitons. Finally, we discuss the implications of our results to several phenomenological issues involving neutron star phase transitions. Comment: 22 pages, 7 figures; Typos fixed in Acknowledgements and BibliographyPhysical Review C 01/2002; · 3.88 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**We study the equation of state (EOS) of kaon-condensed matter including the effects of temperature and trapped neutrinos. It is found that the order of the phase transition to a kaon-condensed phase, and whether or not Gibbs' rules for phase equilibrium can be satisfied in the case of a first order transition, depend sensitively on the choice of the kaon-nucleon interaction. The main effect of finite temperature, for any value of the lepton fraction, is to mute the effects of a first order transition, so that the thermodynamics becomes similar to that of a second order transition. Above a critical temperature, found to be at least 30--60 MeV depending upon the interaction, the first order transition disappears. The phase boundaries in baryon density versus lepton number and baryon density versus temperature planes are delineated. We find that the thermal effects on the maximum gravitational mass of neutron stars are as important as the effects of trapped neutrinos, in contrast to previously studied cases in which the matter contained only nucleons or in which hyperons and/or quark matter were considered. Kaon-condensed EOSs permit the existence of metastable neutron stars, because the maximum mass of an initially hot, lepton-rich protoneutron star is greater than that of a cold, deleptonized neutron star. The large thermal effects imply that a metastable protoneutron star's collapse to a black hole could occur much later than in previously studied cases that allow metastable configurations. Comment: 24 pages, 17 figuresPhysical Review C 09/2000; 62(3):035803. · 3.88 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**We investigate a first-order phase transition from hadronic matter to antikaon condensed matter during the cooling stage of protoneutron stars. The phase transition proceeds through the thermal nucleation of antikaon condensed matter. In this connection we study the effect of shear viscosity on the thermal nucleation rate of droplets of antikaon condensed matter. Here we adopt the same equation of state for the calculation of shear viscosity and thermal nucleation time. We compute the shear viscosity of neutron star matter composed of neutrons, protons, electrons and muons using the relativistic mean field model. The prefactor in the nucleation rate which includes the shear viscosity, is enhanced by several orders of magnitude compared with the $T^4$ approximation of earlier calculations. Consequently the thermal nucleation time in the $T^4$ approximation overestimates our result. Further the thermal nucleation of an antikaon droplet might be possible in our case for surface tension smaller than 20 MeV fm$^{-2}$.Physical review D: Particles and fields 12/2010; 82.

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