SEARCH FOR LONG-LIVED NEUTRAL PARTICLES DECAYING INTO "LEPTON-JETS" WITH THE ATLAS DETECTOR IN PROTON-PROTON COLLISION DATA AT $\sqrt(s)$ = 13 TEV

Several models of elementary particle physics beyond the Standard Model, predict the existence of neutral particles that can also be long lived and decay in collimated jets of light leptons and hadrons (lepton-jets). The present contribution refers to the search for displaced lepton-jets in proton-proton collision data sample recorded at $\sqrt{s}$=13 TeV during 2015 and 2016 data tacking periods. The selected events are compared with the Standard Model expectations and with various BSM predictions.