Superfluidity of Λ hyperons in neutron stars

We study the S-1(0) superfluidity of Lambda hyperons in neutron star matter and neutron stars. We use the relativistic mean field (RMF) theory to calculate the properties of neutron star matter. In the RMF approach, the meson-hyperon couplings are constrained by reasonable hyperon potentials that include the updated information from recent developments in hypernuclear physics. To examine the S-1(0) pairing gap of Lambda hyperons, we employ several Lambda interactions based on the Nijmegen models and used in double-Lambda hypernuclei studies. It is found that the maximal pairing gap obtained is a few tenths of a MeV. The magnitude and the density region of the pairing gap are dependent on the Lambda Lambda interaction and the treatment of neutron star matter. We calculate neutron star properties and find that whether the S-1(0) superfluidity of Lambda hyperons exists in the core of neutron stars mainly depends on the Lambda Lambda interaction used.