2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/128544Residual correlations between decay products due to a combination of both correlations between parents at small relative velocities and small decay momenta are discussed. Residual correlations between photons from pion decays are considered as a new possible source of information on direct photon fraction. Residual correlations in $pγ$ and $pΛ$ systems due to $pΣ^0$ interaction in final state are predicted based on the $pΣ^0$ low energy scattering parameters deduced from the spin-flavour SU$_6$ model by Fujiwara et al. including effective meson exchange potentials and explicit flavour symmetry breaking to reproduce the properties of the two-nucleon system and the low-energy hyperon-nucleon cross section data. The $pγ_{Σ^0}$ residual correlation is concentrated at $k^* \approx 70$ Mev/$c$ and its shape and intensity appears to be sensitive to the scattering parameters and space-time dimensions of the source. The $pΛ_{Σ^0}$ residual correlation recovers the negative parent $pΣ^0$ correlation for $k^* > 70$ Mev/$c$. The neglect of this negative residual correlation would lead to the underestimation of the parent $pΛ$ correlation effect and to an overestimation of the source size.10 pages, 5 figuresNuclear TheoryHigh Energy Physics - Phenomenologytext