Kaon–Deuteron Correlation Function from an Effective Field Theory Approach

Abstract

We present a study of femtoscopic correlation functions for \(K^{-}d\) and \(K^{+}d\) pairs, and compare our results with recent measurements by the ALICE Collaboration in both Pb–Pb and high-multiplicity \(pp\) collisions. The kaon–deuteron wave functions are derived from scattering amplitudes using a unitarized chiral effective theory model describing the elementary interactions of \(K^{\pm }\) mesons with nucleons. We then evaluate the \(K^{\pm }d\) strong scattering amplitudes by solving the Faddeev equations within two distinct frameworks: the Impulse Approximation and the Fixed Center Approximation, which accounts for multiple scatterings. We also incorporate the long-range Coulomb effects between the kaon and the deuteron. We show that the \(K^{-}d\) correlation function exhibits large sensitivity to both the size of the emitting source and the relative momentum of the pair, being heavily influenced by rescattering processes. In contrast, the \(K^{+}d\) correlation function is dominated by the weakly repulsive \(K^{+}N\) interaction, showing deviations from purely Coulombic behavior only at small emission source sizes. Our predictions are in agreement with the ALICE experimental data, and also with the energy-shift and width of the \(1s\) level of the kaonic deuterium preliminary results from the SIDDHARTA 2 Collaboration. Published by the Jagiellonian University 2026 authors