Source radius r$_0$ as a function of $\langle m_{\rm T} \rangle$ for the assumption of a purely Gaussian source. The blue crosses result from fitting the p$-$p correlation function with the strong Argonne $v_{18}$ potential. The green squared crosses (red diagonal crosses) result from fitting the p$-\Lambda$ correlation functions with the strong $\chi$EFT LO (NLO ) potential. Statistical (lines) and systematic (boxes) uncertainties are shown separately.