Forecasting dark showers at Belle II

Abstract

Dark showers from strongly interacting dark sectors that confine at the GeV scale can give rise to novel signatures at $e^{+}{e}^{-}$ colliders. In this work, we study the sensitivity of $B$ factory experiments to dark showers produced through an effective interaction arising from a heavy off-shell mediator. We show that a prospective search for displaced vertices from GeV-scale long-lived particles at Belle II can improve the sensitivity to dark showers substantially compared to an existing search at BaBar. We compare the sensitivity of searches for displaced signals to searches for promptly produced resonances at BaBar and KLOE and calculate sensitivity projections for a single-photon search at Belle II to invisible dark showers produced through an effective interaction. The underlying structure of the effective interaction can be resolved at higher-energy experiments, where the mediator can be produced on-shell. To study the resulting constraints, we update electroweak precision bounds on kinetically mixed $Z^{\prime }$ bosons and reinterpret a search for low-mass di-muon resonances at LHCb in terms of dark showers. We find that LHCb and Belle II are most sensitive to different particle decay lengths, underscoring the complementarity of LHC and intensity frontier experiments.

21 pages, 9 figures; v2: additional references, minor correction to figure 9, conclusions unchanged; v3: matches published version

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Cited by in corpus (6)

• Dark showers from Z-dark Z' mixing
• Dark matter relic density in strongly interacting dark sectors with light vector mesons
• Sub-GeV dark matter and multi-decay signatures from dark showers at beam-dump experiments
• New physics particles mixing with mesons: production in the fragmentation chain
• Systematic analysis of search strategies for $L_{\mu }-L_{\tau }$ gauge bosons at Belle II
• Semi-Visible Dark Photon Phenomenology at the GeV Scale