Extracting $p\Lambda$ scattering lengths from heavy ion collisions

The $p-\Lambda \oplus \bar{p}-\bar{\Lambda}$ and $\bar{p}-\Lambda \oplus p-\bar{\Lambda}$ correlation functions for 10% most central Au+Au collisions at top RHIC energy $\sqrt{s_{NN}}=200$ GeV are modeled with Lednicky and Lyuboshitz analytical formula using the source radii extracted from the hydrokinetic model (HKM) simulations. For the baryon-antibaryon case the corresponding spin-averaged strong interaction scattering length is obtained by fitting the STAR correlation function. In contrast to the experimental results, where extracted $p\bar{\Lambda}$ source radius value was found $\sim 2$ times smaller than the corresponding $p\Lambda$ one, the calculations in HKM show both $p\Lambda$ and $p\bar{\Lambda}$ effective source radii to be quite close, as expected from theoretical considerations. To obtain the satisfactory fit to the measured baryon-antibaryon correlation function at this large source radius value, the modified analytical approximation to the correlation function, effectively accounting for the residual correlations, is utilized.