We generalize the recently proposed mechanism by Demirtas, Kim, McAllister and Moritz [1] for the explicit construction of type IIB flux vacua with |W 0 | ≪ 1 to the region close to the conifold locus in the complex structure moduli space. For that purpose tools are developed to determine the periods and the resulting prepotential close to such a codimension one locus with all the remaining moduli still in the large complex structure regime. As a proof of principle we present a working example for the Calabi-Yau manifold ℙ 1,1,2,8,12. [24]

Taking the anti-de Sitter minimum of KKLT and the large volume scenario at face value, we argue for the existence of logarithmic quantum corrections to the AdS scale separation and AdS distance conjectures. If these conjectures receive such corrections, it is natural to suspect that they also arise for other swampland conjectures, in particular the dS swampland conjecture. We point out that the proposed log-corrections are in accord with the implications of the recently proposed trans-Planckian censorship conjecture. We also comment on the emergence proposal in the context of both perturbative flux models and the KKLT construction.

In the context of the recently proposed L ∞ bootstrap approach, the question arises whether the so constructed gauge theories are unique solutions of the L ∞ relations. Physically it is expected that two gauge theories should be considered equivalent if they are related by a field redefinition described by a Seiberg-Witten map. To clarify the consequences in the L ∞ framework, it is proven that Seiberg-Witten maps between physically equivalent gauge theories correspond to quasi-isomorphisms of the underlying L ∞ algebras. The proof suggests an extension of the definition of a Seiberg-Witten map to the closure conditions of two gauge transformations and the dynamical equations of motion.

We investigate string-phenomenological questions of Hull's exotic superstring theories with Euclidean strings/branes and multiple times. These are known to be plagued by pathologies like the occurrence of ghosts. On the other hand, these theories exhibit de Sitter solutions. Our special focus lies on the question of the coexistence of such de Sitter solutions and ghost-free brane worlds. To this end, the world-sheet CFT description of Euclidean fundamental strings is generalized to include also the open string/D-brane sector. Demanding that in the "observable" gauge theory sector the gauge fields themselves are non-ghosts, a generalization of the dS swampland conjecture is found.

We point out that the de Sitter swampland conjecture would be falsified if classical fluxed Type IIA orientifold vacua with a single non‐BPS D7‐brane were indeed part of the string theory landscape. In other words, the dS swampland conjecture implies the cancellation of K‐theory charges on a compact space.