Searching for light neutralinos with a displaced vertex at the LHC

Abstract

We study a bino-like light neutralino ( {overset{sim }{chi}}_1^0 ) produced at the LHC from the decay of a scalar lepton ( tilde{e}_L ) through the process pp → tilde{e}_L → e{overset{sim }{chi}}_1^0 in the context of R-parity-violating (RPV) supersymmetry where {overset{sim }{chi}}_1^0 is the lightest supersymmetric particle. For small masses and RPV couplings, the neutralino is naturally long-lived and its decay products can be identified as displaced tracks. Following existing searches, we propose a displaced-vertex search strategy for such a light neutralino with a single RPV coupling switched on, {lambda}_{111}^{prime } , in the mass range 10 GeV ≲ {m}_{{overset{sim }{chi}}_1^0} ≲ 230 GeV. We perform Monte Carlo simulations and conclude that at the high-luminosity LHC, the proposed search can probe values of {lambda}_{111}^{prime } down to two orders of magnitude smaller than current bounds and up to 40 times smaller than projected limits from monolepton searches.