The energies of the degenerate spin-flip doublet $(3^{+}/2,5^{+}/2)$ of ${}_{\Lambda }^9\text{Be}$ and of the $2^{+}$ state of ${}_{\Lambda \Lambda }^{10}\text{Be}$ are analyzed in the α cluster model using a phenomenological dispersive three-body $\Lambda \alpha \alpha$ force that reproduces the ground state energy of ${}_{\Lambda }^9\text{Be}$. Two types of phenomenological $\Lambda \alpha$ and $\alpha \alpha$ potentials and a few s-state $\Lambda \Lambda$ potentials are taken as input. The energies of the excited states of the hypernuclei, treated as three- and four-body systems, calculated using the Variational Monte Carlo method, are in good agreement with the experimental values. Our results demonstrate that the existing data are insensitive to whether one employs a dispersive $\Lambda \alpha \alpha$ force along with potentials in the relative angular momentum state $l=0$ and 2 as in the present work or whether one uses nonlocal $\Lambda \alpha$ potential as in earlier analyses.

• Received 27 September 2006
• Publisher error corrected 28 December 2006

DOI:https://doi.org/10.1103/PhysRevC.74.064316