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

A bstract We study the weak gravity conjecture, the swampland distance conjecture and the emergence proposal for N = 1 orientifold compactifications of type IIB string theory with O3-/O7-planes. We allow for orientifold projections with h + 2 , 1 ≠ 0 which gives rise to closed-string U(1) gauge fields, and our findings show that certain structures present for N = 2 compactifications are not present for 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 sector.