NUC In the literature: open

Density dependence of the $\Lambda$ potential in nuclear matter

In plain words

Binding energies of $\Lambda$ hyperons in heavy hypernuclei show that a $\Lambda$ feels an attraction of about $30\,\mathrm{MeV}$ inside ordinary nuclear matter. Whether this attraction turns into repulsion at two to three times nuclear density decides whether Lambdas appear in neutron stars.

Precise statement

Determine the Lambda single-particle potential $U_{\Lambda}(n)$ in symmetric and pure neutron matter for n from $n_0\ \text{to}\ 3n_0$ ($n_0=0.16\ \mathrm{fm}^{-3}$), given $U_{\Lambda}(n_0)$ of about $-30\ \mathrm{MeV}$ from hypernuclear binding systematics. Answer: $U_{\Lambda}(n)$ with quantified uncertainty from $\Lambda N$ and $\Lambda NN$ interactions constrained by hypernuclear binding energies, femtoscopic correlations and lattice QCD, and the resulting Lambda threshold density in beta-equilibrated matter.

What would settle it

A $\Lambda NN$ three-body force fixed by $p-p-\Lambda$ and $d-\Lambda$ femtoscopy and by binding energies of medium and heavy hypernuclei, used in quantum Monte Carlo or chiral many-body calculations of hyperonic matter.

Status in the literature

Unverified note

STAR reported the first deuteron-$\Lambda$ correlation measurement at RHIC in 2025 (arXiv 2511.15493), a new constraint on the three-body sector.