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 Λ–Λ bound state, the H-dibaryon, derived from Λ–Λ femtoscopic measurements by the ALICE collaboration. The results are obtained from a new measurement using the femtoscopy technique in (Figure presented.) collisions at s=13 TeV and p–Pb collisions at s_NN=5.02 TeV, combined with previously published results from (Figure presented.) collisions at s=7 TeV. The Λ–Λ scattering parameter space, spanned by the inverse scattering length f₀ ⁻¹ and the effective range d₀, is constrained by comparing the measured Λ–Λ 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 Λ–Λ interaction. The region in the (f₀ ⁻¹,d₀) plane which would accommodate a Λ–Λ bound state is substantially restricted compared to previous studies. The binding energy of the possible Λ–Λ bound state is estimated within an effective-range expansion approach and is found to be B_ΛΛ=3.2_−2.4 ^+1.6(stat)_−1.0 ^+1.8(syst) MeV.