`` $\Lambda -\Sigma$ conversion in ${}_{\Lambda }^4$He and ${}_{\Lambda }^4$H based on four-body calculation

Abstract

Precise four-body calculations for ${}_{\Lambda }^4$He and ${}_{\Lambda }^4$H have been performed in the framework of the variational method with Jacobian-coordinate Gaussian-basis functions. All the rearrangement channels of both $NNN\Lambda$ and $NNN\Sigma$ are explicitly taken into account for the first time with the use of realistic $NN$ and $YN$ interactions. The role of $\Lambda$-$\Sigma$ conversion and the amount of the virtual $\Sigma$-component in ${}_{\Lambda }^4$He and ${}_{\Lambda }^4$H are discussed.

Comments: 14 pages, 8figures, submitted to Physical Review C