Long-Lived Fermions at AL3X

Abstract

Recently Gligorov $\text{et al.}$ [arXiv:1810.03636] proposed to build a cylindrical detector named '$\text{AL3X}$' close to the $\text{ALICE}$ experiment at interaction point (IP) 2 of the LHC, aiming for discovery of long-lived particles (LLPs) during Run 5 of the HL-LHC. We investigate the potential sensitivity reach of this detector in the parameter space of different new-physics models with long-lived fermions namely heavy neutral leptons (HNLs) and light supersymmetric neutralinos, which have both not previously been studied in this context. Our results show that the $\text{AL3X}$ reach can be complementary or superior to that of other proposed detectors such as $\text{CODEX-b}$, $\text{FASER}$, $\text{MATHUSLA}$ and $\text{SHiP}$.

Comments: 17 pages, 5 figures, 2 tables