Constraints from Λ hypernuclei on the ΛNN content of the Λ-nucleus potential

A depth of D_Λ≈−28 MeV for the Λ-nucleus potential was confirmed in 1988 by studying Λ binding energies deduced from (π⁺,K⁺) spectra measured across the periodic table. Modern two-body hyperon-nucleon interaction models require additional interaction terms, most likely ΛNN three-body terms, to reproduce D_Λ. Here we apply a suitably constructed Λ-nucleus density dependent optical potential to binding energy calculations of observed 1s_Λ and 1p_Λ states in the mass range 12≤A≤208. The resulting ΛNN contribution to D_Λ, about 14 MeV repulsion at symmetric nuclear matter density ρ₀=0.17 fm⁻³, makes D_Λ increasingly repulsive at ρ≳3ρ₀, leading possibly to little or no Λ hyperon content of neutron-star matter. This suggests in some models a stiff equation of state that may support two solar-mass neutron stars.