Measurement of strange baryon-antibaryon interactions with femtoscopic correlations

Two-particle correlation functions were measured for $\mathrm{p}\bar{\mathrm{p}}$, $\mathrm{p}\bar{\mathrm{\Lambda }}$, $\bar{\mathrm{p}}\mathrm{\Lambda }$, and $\mathrm{\Lambda }\bar{\mathrm{\Lambda }}$ pairs in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$TeVand$\sqrt{s_{\rm NN}}=5.02$ TeV recorded by the ALICE detector. From a simultaneous fit to all obtained correlation functions, real and imaginary components of the scattering lengths, as well as the effective ranges, were extracted for combined $\mathrm{p}\bar{\mathrm{\Lambda }}$ and $\rm \overline{p}\Lambda$pairsand,forthefirsttime,for$\Lambda\overline{\Lambda}$ pairs. Effective averaged scattering parameters for heavier baryon-antibaryon pairs, not measured directly, are also provided. The results reveal similarly strong interaction between measured baryon-antibaryon pairs, suggesting that they all annihilate in the same manner at the same pair relative momentum $k^{\ast }$. Moreover, the reported significant non-zero imaginary part and negative real part of the scattering length provide motivation for future baryon-antibaryon bound state searches.