Search for light long-lived neutral particles produced in pp collisions at ?s=13TeV and decaying into collimated leptons or light hadrons with the ATLAS detector - Aad G; Abbott B; Abbott DC; Abud AA; Abeling K; Abhayasinghe DK; Abidi SH; AbouZeid OS; Abraham NL; Abramowicz H; Abreu H; Abulaiti Y; et al. (European Physical Journal c, 2020)