Femtoscopic correlation function for the $T_{cc}(3875)^+$ state

Abstract

We have conducted a study of the femtoscopic correlation functions for the $D^0D^{*+}$ and $D^+D^{*0}$ channels that build the $T_{cc}$ state. We develop a formalism that allows us to factorize the scattering amplitudes outside the integrals in the formulas, and the integrals involve the range of the strong interaction explicitly. For a source of size of 1 fm, we find values for the correlation functions of the $D^0 D^{*+}$ and $D^+D^{*0}$ channels at the origin around 30 and 2.5, respectively, and we see these observables converging to unity already for relative momenta of the order of 200 MeV. We conduct tests to see the relevance of the different contributions to the correlation function and find that it mostly provides information on the scattering length, since the presence of the source function in the correlation function introduces an effective cut in the loop integrals that makes them quite insensitive to the range of the interaction.