Swampland conjectures for type IIB orientifolds with closed-string U(1)s

Abstract

Abstract We study the weak gravity conjecture, the swampland distance conjecture and the emergence proposal for $$ \mathcal{N} $$ N = 1 orientifold compactifications of type IIB string theory with O3-/O7-planes. We allow for orientifold projections with $$ {h}_{+}^{2,1}\ne 0 $$ h + 2 , 1 ≠ 0 which gives rise to closed-string U(1) gauge fields, and our findings show that certain structures present for $$ \mathcal{N} $$ N = 2 compactifications are not present for $$ \mathcal{N} $$ N = 1. In particular, assumptions about stability have to be relaxed and we encounter an ambiguity for the emergence of gauge symmetries associated with the $$ {h}_{+}^{2,1} $$ h + 2 , 1 sector.