Possibility of ΛΛ pairing and its dependence on background density in a relativistic Hartree-Bogoliubov model -: art. no. 015801

We calculate a LambdaLambda pairing gap in binary mixed matter of nucleons and Lambda hyperons 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 rho(N)=2.5rho(0) the LambdaLambda pairing gap is very small, and that a 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 LambdaLambda attraction on the gap is also examined in connection with the revised information of the LambdaLambda interaction.