Example fits of Eq. \ref{eq:fit1} to the ratio of the data toPYTHIA8 correlation functions for K$^0_{\rm S}$K$^0_{\rm S}$ in pp collisions at $\sqrt{s}=$ 5.02 TeV (left) and 13 TeV (right). Statistical uncertainties are shown as error bars and systematic uncertainties are shown as boxes.