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 search for displaced lepton-jets in a 3.4 fb$^{-1}$ proton-proton collision data sample recorded by ATLAS at $\sqrt{s}$=13 TeV during 2015 data taking period is summarized. The selected events are compared with the Standard Model expectations and with BSM predictions.