ΛΛ interaction from relativistic heavy-ion collisions

We investigate the two-particle intensity correlation function of Λ in relativistic heavy-ion collisions. We find that the behavior of the ΛΛ correlation function at small relative momenta is fairly sensitive to the interaction potential and collective flows. By comparing the results of different source functions and potentials, we explore the effect of intrinsic collective motions on the correlation function. We find that the recent STAR data give a strong constraint on the scattering length and effective range of ΛΛ interaction, as -1.8fm⁻¹<1/a0<-0.8fm⁻¹ and 3.5fm<reff<7fm, respectively, if Λ samples do not include the feed-down contribution from long-lived particles. We find that the feed-down correction for Σ⁰ decay reduces the sensitivity of the correlation function to the detail of the ΛΛ interaction. As a result, we obtain a weaker constraint, 1/a0<-0.8 fm⁻¹. Implication for the signal of existence of H-dibaryon is discussed. Comparison with the scattering parameters obtained from the double Λ hypernucleus may reveal in-medium effects in the ΛΛ interaction