Abstract
We study vector portal dark matter models where the mediator couples only to leptons. In spite of the lack of tree-level couplings to colored states, radiative effects generate interactions with quark fields that could give rise to a signal in current and future experiments. We identify such experimental signatures: scattering of nuclei in dark matter direct detection; resonant production of lepton–antilepton pairs at the Large Hadron Collider; and hadronic final states in dark matter indirect searches. Furthermore, radiative effects also generate an irreducible mass mixing between the vector mediator and the Z boson, severely bounded by ElectroWeak Precision Tests. We use current experimental results to put bounds on this class of models, accounting for both radiatively induced and tree-level processes. Remarkably, the former often overwhelm the latter.
Highlights
Interacting Massive Particles (WIMPs) are motivated dark matter (DM) candidates testable with multiple and complementary methods [1,2,3]
For a mediator coupled to electrons with couplings of order one, the subsequent limits on the mediator mass are of order mV 400 − 500 GeV for DM lighter than ∼ 100 GeV [61]
Though (g − 2)μ constraints still apply for treelevel couplings to muons, the annihilation cross section is suppressed by the mass of the lepton in the final state, leading to weaker indirect detection limits
Summary
Interacting Massive Particles (WIMPs) are motivated dark matter (DM) candidates testable with multiple and complementary methods [1,2,3]. Our work extends the previous literature on vector portal leptophilic models by identifying new processes arising from such loop-induced couplings and imposing the associated experimental constraints. We find the RG-induced contributions to the coupling between the mediator and light quarks We constrain this coupling using data from LHC searches for dilepton resonances. Still using the RG-induced couplings between the mediator and light quarks, but this time at a much lower energy, we compute the DM elastic scattering rate of target nuclei and we impose direct detection bounds. If the mediator couples to the DM axial-vector current, we point out a contribution to the scattering rate proportional to the Yukawa coupling of the lepton under consideration This effect was first pointed out in Ref.
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