Primordial black holes, zero-point energy and the CMB: The cosmic   connection
  We propose a possible resolution to the cosmological constant problem through a scenario in which the universe is composed of three components: matter, radiation (CMB) and vacuum energy such that vacuum energy is not constant and is decaying into the matter component. Matter in this scenario consists of baryonic matter and primordial black holes (PBHs) as the dark matter. Local equilibrium condition between PBHs and CMB confines the mass and the radius of PBHs. The mechanism accounting for the decaying process is nothing but the absorption of vacuum energy modes by the PBHs up to a wavelength of the order of their radius. Acting as a natural cut-off on the wavelength of vacuum energy modes, this leads to the observed value for the vacuum energy density. 
S. Zeynizadeh and M. Nouri-Zonoz
gr-qc astro-ph.HE hep-ph hep-th