Study of the Lambda-Lambda interaction with femtoscopy correlations in pp and p-Pbcollisions at the LHC

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 root s = 13 TeV and p-Pb collisions at root s(NN) = 5.02 TeV, combined with previously published results from pp collisions at root 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(-2.4)(+1.6)(stat)(-1.0)(+1.8)(syst) MeV. (C) 2019 The Author(s). Published by Elsevier B.V.