Resolving the hypernuclear overbinding problem in pionless effective field theory
Lorenzo Contessi🇮🇱 · Nir Barnea🇮🇱 · Avraham Gal🇮🇱
We address the -hypernuclear `overbinding problem' in light hypernuclei which stands for a 1--3 MeV excessive separation energy calculated in He. This problem arises in most few-body calculations that reproduce ground-state separation energies in the lighter hypernuclei within various hyperon-nucleon interaction models. Recent pionless effective field theory nuclear few-body calculations are extended in this work to hypernuclei. At leading order, the low-energy constants are associated with scattering lengths and the low-energy constants are fitted to separation energies () for . The resulting pionless-EFT interaction reproduces in few-body stochastic variational method calculations the reported value He)=3.120.02 MeV within a fraction of MeV over a broad range of momentum-space cut-off parameters. Possible consequences and extensions to heavier hypernuclei and to neutron-star matter are discussed.