Searching for super-WIMPs in leptonic heavy meson decays

We study constraints on the models of bosonic super-weakly interacting particle (super-WIMP) dark matter (DM) with DM masses mX∼O(1-100) keV from leptonic decays M→ℓν¯ℓ+X, where M=B±,D±,Ds± is a heavy meson state. We focus on two cases where X denotes either a light pseudoscalar (axion-like), or a light vector state that couples to the standard model (SM) through kinetic mixing. We note that for a small DM mass these decays are separately sensitive to DM couplings to quarks, but not its mass.