Long-lived light neutralinos at Belle II

Abstract

We consider light neutralinos of mass about 1 GeV, produced from $\tau$ lepton rare decays at Belle II, in the context of R-parity-violating (RPV) supersymmetry. With large and clean samples of $\tau$ leptons produced at the Belle II experiment, excellent sensitivity to such light neutralinos with the exotic signatures of displaced vertices is expected. We focus on two benchmark scenarios of single RPV operators, ${\lambda }_{311}^{\prime }{L}_3{Q}_1{\bar{D}}_1$ and ${\lambda }_{312}^{\prime }{L}_3{Q}_1{\bar{D}}_2$, which induce both the production and decay of the lightest neutralino. For the reconstruction of a displaced vertex, we require at least two charged pions in the final states. We perform Monte-Carlo simulations for both signal and background events, and find that Belle II can explore regions in the parameter space competitive with other probes. In particular, for the ${\lambda }_{311}^{\prime }$ scenario, it can put limits up to two orders of magnitude stronger than the current bounds.

v1, 15 pages plus appendices, 6 figures, 3 tables; v2, minor changes, matched with the published version

References in corpus (12)

• PYTHIA 6.4 Physics and Manual
• Probing a Secluded U(1) at B-factories
• Revised constraints and Belle II sensitivity for visible and invisible axion-like particles
• Relativistic treatment of the decay constants of light and heavy mesons
• Can neutralinos in the MSSM and NMSSM scenarios still be light?
• Bounds on R-parity violating supersymmetric couplings from leptonic and semi-leptonic meson decays
• Invisible and displaced dark matter signatures at Belle II
• Probing leptogenesis with GeV-scale sterile neutrinos at LHCb and BELLE II
• Hunting the lightest lightest neutralinos
• Rare meson decays into very light neutralinos
• Estimate of the branching fraction ${\tau }^{-}\to \eta {\pi }^{-}{\nu }_{\tau }$, the $a_0^{-}(980)$, and non-standard weak interactions
• Estimate of the Branching Fraction of tau --> pi eta' nu_tau