Searching for light neutralinos with a displaced vertex at the LHC

Abstract

We study a bino-like light neutralino (${\tilde{\chi }}_1^0$) produced at the LHC from the decay of a scalar lepton (${\tilde{e}}_L$) through the process $pp\to {\tilde{e}}_L\to e{\tilde{\chi }}_1^0$ in the context of R-parity-violating (RPV) supersymmetry where ${\tilde{\chi }}_1^0$ 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 $10\text{mbox}GeV\lesssim m_{{\tilde{\chi }}_1^0}\lesssim 230\text{mbox}GeV$. 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 stronger than projected limits from monolepton searches.

Comments: 16 pages, 6 figures; v2: comment added, matches version to be published in JHEP; v3: figure 2 corrected