arXiv subjects

Lukas Kaufmann

Publications and source records attributed to Lukas Kaufmann.

4 recordsLinked to original sources

arXiv2026

On Quantum Obstructions in Type IIA Orientifolds

Quantum corrections can severely modify or even remove classical infinite distance limits in four-dimensional gravity theories with minimal N=1 supersymmetry. In this note we study this effect for infinite distance directions in the classical K\"ahler moduli sector of Type IIA orientifolds at fixed four-dimensional dilaton. We present several independent arguments why such infinite distance directions are absent at the quantum level. These involve the worldsheet theory of EFT strings and the putative asymptotically massless tower of particles. Key insights are provided by the uplift to M-theory on G2 manifolds, which allows for a unified treatment of quantum obstructions of seemingly different origin in the dual Type IIB/F-theory frame. Our results apply also to the Type IIA dual of infinite distance limits for which no quantum obstruction could be detected in the Type IIB frame in previous work. In conclusion, infinite distance limits in the part of the orientifold moduli space descending from a 4d N=2 vector multiplet sector are only possible at the quantum level if also some of the remaining moduli are taken to infinity.

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arXiv2026

Quantum obstructions for $N=1$ infinite distance limits -- Part II: K\"ahler obstructions

We continue our analysis of quantum corrections in the complex structure moduli space of four-dimensional Type IIB/F-theory compactifications with N=1 supersymmetry. We find that limits in the complex structure moduli space of F-theory generically induce a strong backreaction on other sectors of the theory, reflecting the non-factorisation of the field space in genuine $N=1$ theories at the quantum level. Our focus is on quantum corrections to the K\"ahler moduli in F-theory on Calabi-Yau fourfolds and proceeds in two independent ways: A detailed analysis of the worldsheet theory of candidate EFT strings for pure complex structure infinite distance limits reveals a mismatch with expectations based on the classical effective action and points to a quantum obstruction of the limit. Complementary to this, we confirm, in large classes of theories, the existence of significant complex structure dependent quantum corrections to the action of BPS instantons which at tree-level are governed by the K\"ahler moduli. As the quantum corrections become uncontrolled at large complex structure, they require a co-scaling of the K\"ahler moduli to maintain perturbative control. As a result, the naive, classical effective action does not provide an accurate description of pure large complex structure regimes. We comment on possible implications for string phenomenology, specifically with regard to model building and moduli stabilisation.

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arXiv2026

Quantum obstructions for $N=1$ infinite distance limits -- Part I: $g_s$ obstructions

We analyse quantum obstructions to classical infinite distance limits in four-dimensional string compactifications with N=1 supersymmetry. Such quantum effects signal a severe departure from the perturbative effective action and can be of considerable importance for string model building. Our focus is on the complex structure moduli space of Type IIB orientifolds with O7/O3-planes and its F-theory description. In this first part of our analysis, we investigate the behaviour of $g_s$ corrections in infinite distance complex structure limits. Our main finding is that, depending on the location of the O7-plane, non-perturbative corrections in $g_s$ can become unsuppressed, thus obstructing a perturbative Type IIB description in the corresponding asymptotic region of the field space. In particular, this applies to large complex structure limits. To show this, we study the F-theory description of the Type IIB orientifold, in which all pure $g_s$ corrections are encoded in the (classical) geometry of an elliptic Calabi-Yau fourfold. This $g_s$-corrected moduli space is found to differ significantly from the classical moduli space. In extreme cases the classical infinite distance degeneration can be completely removed at the $g_s$-corrected quantum level. The behaviour of $\alpha'$ corrections, as well as implications for string model building, are discussed in a companion paper.

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arXiv2024

Asymptotics of 5d Supergravity Theories and the Emergent String Conjecture

We invoke probe brane arguments to classify the asymptotic behavior of general five-dimensional supergravity theories with eight supercharges near infinite distance boundaries of the vector multiplet moduli space. Imposing consistency of supergravity strings we derive several constraints on the Chern-Simons couplings entering the prepotential, including their non-negativity. This establishes a classification of infinite distance limits analogous to those for theories obtained as Calabi-Yau compactifications, but without having to assume a geometric or string theoretic origin. All infinite distance limits are found to be either vector or tensor limits, depending on the nature of the gauge potential becoming weakly coupled at the fastest rate. In particular, we prove uniqueness results for the asymptotically leading gauge fields. The asymptotic physics along these limits is in perfect agreement with the predictions of the Emergent String Conjecture and hence serves as bottom-up evidence for the latter. Our findings imply that every consistent five-dimensional ${\cal N}=1$ supergravity with a non-compact vector multiplet moduli space either descends from six dimensions or contains a stringy subsector.

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