Study of the Λ–Λ interaction with femtoscopy correlations in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:mi mathvariant="normal">p</mml:mi><mml:mspace width="-0.05em"/><mml:mi mathvariant="normal">p</mml:mi></mml:math> and p–Pb collisions at the LHC

Abstract

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 collisions at s = 13 TeV and p – Pb collisions at s NN = 5.02 TeV, combined with previously published results from collisions at s = 7 TeV. The Λ–Λ scattering parameter space, spanned by the inverse scattering length f 0 − 1 and the effective range d 0 , 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 ( f 0 − 1 , d 0 ) 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 Λ Λ = 3.2 − 2.4 + 1.6 (stat) − 1.0 + 1.8 (syst) MeV.