Ooguri–Vafa version of the Weak Gravity Conjecture

Establish whether, in consistent quantum gravity theories, the Weak Gravity Conjecture bound is never saturated when the charged particle realizing the bound is non-BPS, i.e., prove or refute that any superextremal non-BPS state is strictly above the black-hole extremality bound.

Background

The paper reviews the Weak Gravity Conjecture (WGC) and its variants and notes a stronger expectation proposed by Ooguri and Vafa. In many supersymmetric settings, BPS particles can saturate extremality bounds, but Ooguri–Vafa suggest saturation should not occur for non-BPS states. The authors’ bosonic-string results imply a strict, sublattice form of the WGC for the NSNS sector, which strengthens the Ooguri–Vafa expectation in that context, but the general claim remains a conjecture.