Possibility of ΛΛpairing and its dependence on background density in relativistic Hartree-Bogoliubov model

Abstract

We calculate a ΛΛpairing gap in binary mixed matter of nucleons and Λhyperons within the relativistic Hartree-Bogoliubov model. Lambda hyperons to be paired up are immersed in background nucleons in a normal state. The gap is calculated with a one-boson-exchange interaction obtained from a relativistic Lagrangian. It is found that at background density ρ_{N}=2.5ρ_{0} the ΛΛpairing gap is very small, and that denser background makes it rapidly suppressed. This result suggests a mechanism, specific to mixed matter dealt with relativistic models, of its dependence on the nucleon density. An effect of weaker ΛΛattraction on the gap is also examined in connection with revised information of the ΛΛinteraction.

8 pages, 6 figures, REVTeX 4; substantially rewritten, emphasis is put on the LL pairing in pure neutron matter