Beyond mean-field approach for pear-shaped hypernuclei

Abstract

We develop both relativistic mean field and beyond approaches for hypernuclei with possible quadrupole-octupole deformation or pear-like shapes based on relativistic point-coupling energy density functionals. The symmetries broken in the mean-field states are recovered with parity, particle-number, and angular momentum projections. We take ${}_{\Lambda }^{21}$Ne as an example to illustrate the method, where the $\Lambda$ hyperon is put on one of the two lowest-energy orbits (labeled as ${\Lambda }_s,{\Lambda }_p$), respectively. We find that the $\Lambda$ hyperon in both cases disfavors the formation of a reflection-asymmetric molecular-like ${}^{16}$O$+\alpha$ structure in ${}^{20}$Ne, which is consistent with the Nilsson diagram for the hyperon in $({\beta }_2,{\beta }_3)$ deformation plane. In particular, we show that the negative-parity states with the configuration ${}^{20}$Ne($K^{\pi }=0^{-})\otimes {\Lambda }_s$ are close in energy to those with the configuration ${}^{20}$Ne($K^{\pi }=0^{+})\otimes {\Lambda }_p$, even though they have very different structures. The ${\Lambda }_s$ (${\Lambda }_p$) becomes more and more concentrated around the bottom (top) of the "pear" with the increase of octupole deformation.

arXiv comment7 pages, 6 figures, to be published in SCIENCE CHINA Physics, Mechanics & Astronomy (2019)

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Cited by in corpus (7)

• Ground state properties and potential energy surfaces of ${}^{270}$Hs from multidimensionally-constrained relativistic mean field model
• Angular momentum projection in the deformed relativistic Hartree-Bogoliubov theory in continuum
• Strength of pairing interaction for hyperons in multistrangeness hypernuclei
• Angular momentum and parity projected multidimensionally constrained relativistic Hartree-Bogoliubov model
• The interplay of single-particle and collective motions in the low-lying states of ${}_{\Lambda }^{21}$Ne with quadrupole-octupole correlations
• Generator coordinate method for nuclear octupole excitations: status and perspectives
• Tetrahedral shape and Lambda impurity effect in ${}^{80}$Zr with a multidimensionally constrained relativistic Hartree-Bogoliubov model