Effects of neutron excess in deformed Lambda hypernuclei

Abstract: The neutron excess effect, originating from the vanishing of one part of \(\bm{\tau}_\text{1} \cdot \bm{\tau}_\text{2}\) operator matrix elements, was appropriately considered within the Skyrme-type $\Lambda N N$ three-body interactions and applied to the deformed SHF model. Analysis of a broad range of hypernuclei, from light to heavy masses, shows that the neutron excess effect significantly improves the description of $\Lambda$ binding energies. The underlying mechanism involves reducing the $\Lambda N N$ three-body repulsive interaction by subtracting the neutron excess term, thereby improving the binding energy of the hypernucleus. In addition, the impact of this effect on the $\Lambda$ single-particle potential and the hyperon density distribution is discussed.