Search for a Dark Higgs Boson Produced in Association with Inelastic Dark Matter at the Belle II Experiment

Abstract

Inelastic dark matter models that have two dark matter particles and a massive dark photon can reproduce the observed relic dark matter density without violating cosmological limits. The mass splitting between the two dark matter particles ${\chi }_1$ and ${\chi }_2$, with $m({\chi }_2)>m({\chi }_1)$, is induced by a dark Higgs field and a corresponding dark Higgs boson $h^{\prime }$. We present a search for dark matter in events with two vertices, at least one of which must be displaced from the interaction region, and missing energy. Using a $365\,\mbox{fb}^{-1}$ data sample collected at Belle II, which operates at the SuperKEKB $e^{+}{e}^{-}$ collider, we observe no evidence for a signal. We set upper limits on the product of the production cross section $\sigma \left(e^{+}{e}^{-}\to h^{\prime }{\chi }_1{\chi }_2\right)$, and the product of branching fractions $\mathcal{B}\left({\chi }_2\to {\chi }_1{e}^{+}{e}^{-}\right)\times \mathcal{B}\left(h^{\prime }\to x^{+}{x}^{-}\right)$, where $x^{+}{x}^{-}$ indicates ${\mu }^{+}{\mu }^{-},{\pi }^{+}{\pi }^{-}$, or $K^{+}{K}^{-}$, as functions of $h^{\prime }$ mass and lifetime at the level of $10^{-1}\,\mbox{fb}$. We set model-dependent upper limits on the dark Higgs mixing angle at the level of $10^{-5}$ and on the dark photon kinetic mixing parameter at the level of $10^{-3}$. This is the first search for dark Higgs bosons in association with inelastic dark matter.

References in corpus (27)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• An Introduction to PYTHIA 8.2
• First Dark Matter Search with Nuclear Recoils from the XENONnT Experiment
• Study of the decay K+ => pi+,nu,nubar in the momentum region 140<Ppi<199 MeV/c
• Dark matter and the early Universe: a review
• Minimal Extension of the Standard Model Scalar Sector
• Constraints on sub-GeV hidden sector gauge bosons from a search for heavy neutrino decays
• Dark Matter Search Results from 4.2 Tonne-Years of Exposure of the LUX-ZEPLIN (LZ) Experiment
• Measurement of the very rare $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ decay
• Dark Matter Search Results from 1.54 Tonne$\cdot$Year Exposure of PandaX-4T
• Photon pair production at flavour factories with per mille accuracy
• Invisible and displaced dark matter signatures at Belle II
• Study of the $K_L\to {\pi }^0\nu \overline{\nu }$ Decay at the J-PARC KOTO Experiment
• Search for Long-Lived Particles in $e^{+}{e}^{-}$ Collisions
• Search for a Higgs portal scalar decaying to electron-positron pairs in the MicroBooNE detector
• Long-lived Dark Higgs and Inelastic Dark Matter at Belle II
• Constraints on light scalars from PS191 results
• Dark Higgs Bosons at Colliders
• Dark sector searches with the CMS experiment
• Exploration at the high-energy frontier: ATLAS Run~2 searches investigating the exotic jungle beyond the Standard Model
• Search for long-lived heavy neutral leptons and Higgs portal scalars decaying in the MicroBooNE detector
• Measurement of the integrated luminosity of data samples collected during 2019-2022 by the Belle II experiment
• Constraining Light Thermal Inelastic Dark Matter with NA64
• Search for long-lived particles decaying into muon pairs in proton-proton collisions at $\sqrt{s}=$ 13 TeV collected with a dedicated high-rate data stream
• Search for a long-lived spin-0 mediator in $b\to s$ transitions at the Belle II experiment
• Search for inelastic dark matter in events with two displaced muons and missing transverse momentum in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Observation of the decay $B^0\to J/\psi \omega$ at Belle II

Cited by in corpus (2)

• Probing inelastic sub-GeV dark matter at the DUNE near detector
• Real-time graph neural networks on FPGAs for the Belle II electromagnetic calorimeter