Nucleation of quark matter in neutron star cores

We consider the general conditions of quark droplet formation in high-density neutron matter. The growth of the quark bubble (assumed to contain a sufficiently large number of particles) can be described by means of a Fokker-Planck equation. The dynamics of the nucleation essentially depends on the physical properties of the medium in which it takes place. The conditions for quark bubble formation are analyzed within the framework of both dissipative and nondissipative (with zero bulk and shear viscosity coefficients) approaches. The conversion time of the neutron star to a quark star is obtained as a function of the equation of state of the neutron matter and of the microscopic parameters of the quark nuclei. As an application of the formalism obtained, we analyze the first-order phase transition from neutron matter to quark matter in rapidly rotating neutron star cores, triggered by the gravitational energy released during the spinning down of the neutron star. The endothermic conversion process, via gravitational energy absorption, could take place in a very short time interval, of the order of a few tens of seconds, in a class of dense compact objects with very high magnetic fields, called magnetars.published_or_final_versio