Searching for light neutralinos with a displaced vertex at the LHC

Abstract We study a bino-like light neutralino ( χ ~ 1 0 $$ {\overset{\sim }{\chi}}_1^0 $$ ) produced at the LHC from the decay of a scalar lepton ( e ~ L $$ \tilde{e}_L $$ ) through the process pp → e ~ L $$ \tilde{e}_L $$ → e χ ~ 1 0 $$ e{\overset{\sim }{\chi}}_1^0 $$ in the context of R-parity-violating (RPV) supersymmetry where χ ~ 1 0 $$ {\overset{\sim }{\chi}}_1^0 $$ 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, λ 111 ′ $$ {\lambda}_{111}^{\prime } $$ , in the mass range 10 GeV ≲ m χ ~ 1 0 $$ {m}_{{\overset{\sim }{\chi}}_1^0} $$ ≲ 230 GeV. We perform Monte Carlo simulations and conclude that at the high-luminosity LHC, the proposed search can probe values of λ 111 ′ $$ {\lambda}_{111}^{\prime } $$ down to two orders of magnitude smaller than current bounds and up to 40 times smaller than projected limits from monolepton searches.