Superconducting Strings in High Density QCD

Recently it has been argued that the ground state of high density QCD is likely to be a combination of the CFL-phase along with condensation of the K⁰ field. This state spontaneously breaks a global U(1)_Y symmetry, therefore one would expect the formation of U(1)_Y global strings. We discuss the core structure of these strings and demonstrate that under some conditions the global U(1)_Y symmetry may not be restored inside the string. Instead, K⁺ condensation occurs inside the core of the string if a relevant parameter \cos θ _{K⁰ } ≡ {{m_{K⁰ }² } {/ {{m_{K⁰ }² } {μ _eff² }}} ; . } {μ _eff² }} is larger than some critical value θ<INF>K^°</INF> ≥ θ_crit. If this phenomenon happens, the U(1)_Y strings become superconducting and may considerably influence the magnetic properties of dense quark matter, in particular in neutron stars.