Lambda-Lambda interaction from two-particle intensity correlation in relativistic heavy-ion collisions

We investigate $\mathrm{\Lambda }\mathrm{\Lambda }$ interaction dependence of the $\mathrm{\Lambda }\mathrm{\Lambda }$ intensity correlation in high-energy heavy-ion collisions. By analyzing the correlation data recently obtained by the STAR collaboration based on theoretically proposed $\mathrm{\Lambda }\mathrm{\Lambda }$ interactions, we give a constraint on the $\mathrm{\Lambda }\mathrm{\Lambda }$ scattering length, $-1.25~$\text{fm}$ < a_0 < 0$,suggestingthat$\Lambda\Lambda$ interaction is weakly attractive and there is no loosely bound state. In addition to the fermionic quantum statistics and the $\mathrm{\Lambda }\mathrm{\Lambda }$ interaction, effects of collective flow, feed-down from ${\mathrm{\Sigma }}^0$, and the residual source are also found to be important to understand the data. We demonstrate that the correlation data favor negative $\mathrm{\Lambda }\mathrm{\Lambda }$ scattering length with the pair purity parameter $\lambda =(0.67{)}^2$ evaluated by using experimental data on the ${\mathrm{\Sigma }}^0\mathrm{/}\mathrm{\Lambda }$ ratio, while the positive scattering length could be favored when we regard $\lambda$ as a free fitting parameter.