Foundational uncertainties in computing relic charge at the Planck scale
Establish a first-principles framework for charged particle emission in the final stages of primordial black hole evaporation that (a) ascertains whether the back-reaction of evaporation products on the black hole can be neglected so that emissions can be treated as isolated events, and (b) determines the behavior of the electromagnetic coupling α_EM at or near the Planck scale relevant to charge emission and relic formation.
References
First, it is unclear whether one can neglect the back-reaction of the evaporation products on the BH, and, as a consequence, whether or not the particle emission can be considered as an "individual", isolated event [Page:1976ki]; Second, the charge-to-mass ratio may get large enough that it could significantly affect, or even stop, the evaporation rate: recall that a Planck-mass BH reaches extremality for Q\simeq 12\ e. Third, it is unclear how the running of the electromagnetic coupling \alpha_{\rm EM} behaves at or near the Planck scale, where several layers of new physics possibly come into play through radiative effects.