Abstract
We propose a program at B-factories of inclusive, multi-track displaced vertex searches, which are expected to be low background and give excellent sensitivity to non-minimal hidden sectors. Multi-particle hidden sectors often include long-lived particles (LLPs) which result from approximate symmetries, and we classify the possible decays of GeV-scale LLPs in an effective field theory framework. Considering several LLP production modes, including dark photons and dark Higgs bosons, we study the sensitivity of LLP searches with different number of displaced vertices per event and track requirements per displaced vertex, showing that inclusive searches can have sensitivity to a large range of hidden sector models that are otherwise unconstrained by current or planned searches.
Highlights
Much heavier than the DM mass and DM annihilation is sufficiently feeble that the DM abundance cannot be depleted enough to match observations
In most of these scenarios, there is only one new particle that interacts with the SM, and both its production from and decay to SM states is determined by a single coupling. This single particle can be treated as completely invisible, either because it is meta-stable or because it decays to invisible, stable DM particles. This approach allows for powerful searches for new hiddensector particles by exploiting the very specific production and decay modes predicted by the model, and permits the ready comparison of different experiments using a common set of benchmarks, such as those proposed by the Physics Beyond Colliders working group [4]
We propose several extensions of existing searches for long-lived particles (LLPs) at BABAR [49] and LHCb [51], both of which are inclusive with respect to production mechanism but require exclusive reconstruction of 2-body decays: our proposals include searching for displaced vertices (DVs) with more than two tracks or two DVs in an event
Summary
We consider the set of models where the hidden sector is composed of a mediator, φ, and an LLP, χ; φ and χ could have any spin consistent with the decay φ → χχ We assume that both have masses 10 GeV so that they are accessible for on-shell production at B-factory energies, e+e− → φ + X, φ → χχ, where X is some unspecified SM states that could be produced in association with φ. We list the possible operators OSM subject to the gauge invariance constraints and organize them by operator dimension The latter is key in determining the resulting LLP lifetime τχ ≡ Γ−χ 1, Γχ ∼ mχ mχ Λ. Note that when the operator involves quarks, the actual decay final states are generated by hadronization which may lead to a different number of charged particles than naïvely expected depending on the LLP mass. Dim χOSM 6 leptonici j νki j νk, νiνj νk semi-leptonic iuj dk iuj dk hadronic didjνk, uiujνk, uidj dk didjνk, uiujνk, uidj dk photonic νγ
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