# Study of the $\Lambda$-$\Lambda$ interaction with femtoscopy correlations in pp and p-Pb collisions at the LHC

## TL;DR

This study uses femtoscopy correlations in high-energy collisions to constrain the $\Lambda$-$\Lambda$ interaction, providing new limits on the existence and binding energy of the hypothesized H-dibaryon state.

## Contribution

It offers the first combined femtoscopy analysis in pp and p-Pb collisions at the LHC, significantly restricting the parameter space for a $\Lambda$-$\Lambda$ bound state.

## Key findings

- Data are compatible with a shallow attractive interaction.
- The $\Lambda$-$\Lambda$ bound state, if it exists, has a binding energy around 3.2 MeV.
- The parameter space for a bound state is substantially reduced.

## Abstract

This work presents new constraints on the existence and the binding energy of a possible $\Lambda$-$\Lambda$ bound state, the H-dibaryon, derived from $\Lambda$-$\Lambda$ femtoscopic measurements by the ALICE collaboration. The results are obtained from a new measurement using the femtoscopy technique in pp collisions at $\sqrt{s}=13$ TeV and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV, combined with previously published results from p-Pb collisions at $\sqrt{s}=7$ TeV. The $\Lambda$-$\Lambda$ scattering parameter space, spanned by the inverse scattering length $f_0^{-1}$ and the effective range $d_0$, is constrained by comparing the measured $\Lambda$-$\Lambda$ correlation function with calculations obtained within the Lednicky model. The data are compatible with hypernuclei results and lattice computations, both predicting a shallow attractive interaction, and permit to test different theoretical approaches describing the $\Lambda$-$\Lambda$ interaction. The region in the $(f_0^{-1},d_0)$ plane which would accommodate a $\Lambda$-$\Lambda$ bound state is substantially restricted compared to previous studies. The binding energy of the possible $\Lambda$-$\Lambda$ bound state is estimated within an effective-range expansion approach and is found to be $B_{\Lambda\Lambda}=3.2^{+1.6}_{-2.4}\mathrm{(stat)}^{+1.8}_{-1.0}\mathrm{(syst)}$ MeV.