Searches for exotic particles in multileptonic final states with the ATLAS detector using full Run-2 data

Abstract

Over the past years, the need for an extension of the Standard Model (SM) has become more and more clear, so high-energy physics experiments must explore Beyond the SM (BSM) scenarios, which now constitute an important part of the ATLAS experiment physics program. Searches for multileptonic final states have favourable signatures thanks to the low number of SM processes procuding events with high lepton multiplicity, as these would worsen the signalto- background ratio. In the context of Left-Right Symmetric Model (LRSM) and the Type-III See-Saw mechanism, New Physics events are searched for in several processes, like the production of doubly charged Higgs bosons and the production of heavy neutral or charged leptons. The final states investigated can also involve same-sign light leptons, allowing lepton-number-violation foreseen by the LRSM. ATLAS BSM searches exploring these scenarios with full LHC Run-2 data, for a total luminosity of 139 fb$^-1$ at a centre-of-mass energy of $\sqrt{s}$= 13TeV in $pp$ collisions, are here presented