Effects of Finite Temperature and Pairing Correlations in Multi-$\Lambda$ Hypernuclei

Abstract

The influence of finite temperatures and pairing correlations on the ground state properties of multi $\Lambda$- Ca, Sn and Pb hypernuclei is explored using finite temperature Hartree Fock Bogoliubov approach and contact pairing interaction. A critical temperature is predicted and is in agreement with the Bardeen Cooper Schrieffer relationship $k_B T_C^\Lambda \approx 0.5 \Delta^{T=0}_\Lambda$, beyond which pairing correlations drop to zero. Particle densities, $\Lambda$ single particle energies, and nuclear radii are weakly impacted by pairing as well as by finite temperatures. However, other nuclear properties which are more sensitive to pairing correlations, such as $\Lambda$ pairing gaps, condensation energies, and abnormal densities are also more impacted by finite temperature, especially around the critical temperature. Furthermore, calculations show the occurrence of the pairing re-entrance effect in the $^{280}_{70\Lambda}$Pb hyperon drip line hypernucleus. Our study provides insight into the thermal evolution of $\Lambda$ pairing, i.e. the emergence and vanishing of pairing correlations in multi $\Lambda$ hypernuclei as a function of temperature.