Shape of Lambda hypernuclei in (beta,gamma) deformation plane

Abstract

We study the shape of $\hat{I}›$ hypernuclei in the full (${\hat{I}}^2,{\hat{I}}^3$) deformation plane, including both axially symmetric and triaxial quadrupole deformations. To this end, we use the constrained Skyrme Hartree-Fock+BCS method on the three-dimensional Cartesian mesh. The potential energy surface is analyzed for carbon hypernuclei as well as for sd-shell hypernuclei such as ${}_{\hat{I}}^{27,29}›$Si and ${}_{\hat{I}}^{25,27}›$Mg. We show that the potential energy surface in the (${\hat{I}}^2,{\hat{I}}^3$) plane is similar to each other between the hypernuclei and the corresponding core nuclei, although the addition of $\hat{I}›$ hyperon makes the energy surface somewhat softer along the ${\hat{I}}^3$ direction. Our calculation implies that the energy of the ${\hat{I}}^3$ vibration for ${}_{\hat{I}}^{25,27}›$Mg nuclei is lowered by about 0.15 MeV with respect to that of ${}^{24,26}$Mg nuclei.

10 pages, 15 figures