Study of the Λ–Λ interaction with femtoscopy correlations in pp and p–Pb collisions at the LHC

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 √s = 13 TeV and p-Pb collisions at √sNN = 5.02 TeV, combined with previously published results from pp collisions at √s = 7 TeV. The – scattering parameter space, spanned by the inverse scattering length and the effective range d0, is constrained by comparing the measured lambda–lambda correlation function with calculations obtained within the Lednický 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−1,d0) 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 = 3.2+1.6(stat)+1.8(syst) MeV.