The Swampland Distance Conjecture and towers of tensionless branes

Abstract

The Swampland Distance Conjecture states that at infinite distance in the scalar moduli space an infinite tower of particles become exponentially massless. We study this issue in the context of 4d type IIA and type IIB Calabi-Yau compactifications.We find that for large moduli not only towers of particles but also domain walls and strings become tensionless. We study in detail the case of type IIA and IIB N = 1 CY orientifolds and show how for infinite Kähler and/or complex structure moduli towers of domain walls and strings become tensionless, depending on the particular direction in moduli space. For the type IIA case we construct the monodromy orbits of domain walls in detail. We study the structure of mass scales in these limits and find that these towers may occur at the same scale as the fundamental string scale or the KK scale making sometimes difficult an effective field theory description. The structure of IIA and IIB towers are consistent with mirror symmetry, as long as towers of exotic domain walls associated to non-geometric fluxes also appear. We briefly discuss the issue of emergence within this context and the possible implications for 4d vacua. γ a 2 J = M J ∧ω a , V 4,a = 1 2 γ a 4 J ∧J = M J ∧J ∧ω a , V 6 = 1 3! M J ∧J ∧J . (3.8) So far we have neglected the B-field background. Including it amounts to replacing J → J c and taking the absolute value at the end.Let us now clarify why we have made particular emphasis in the objects forming the basis of 4d domain walls, that is, the objects which are constructed by wrapping only one kind of Dp-brane along one supersymmetric cycle once. The key point is that these are, in general, the only ones for which the tension of the final BPS domain wall can be obtained from the DBI action, since for arbitrary combinations they will usually form bound states, not superpositions. Nevertheless, the important point is that for these general BPS bound states the tension is always bounded from above by the addition of the DBI tensions of each of the components, guaranteeing that all the BPS bound states that are formed by an arbitrary combination of the subset of basis branes that are tensionless, will also be tensionless. We will now consider these general

How many fluxes fit in an EFT?

“…Again, different perturbative regimes in field space may select different sublattices Γ EFT , in agreement with the different hierarchy of scales that holds on each of them, see e.g. the recent analysis in [16]. In fact, one may extend this analysis to understand why even different choices of Γ are considered in opposite regimes of the same class of constructions, like it is illustrated by the weak and strong coupling regimes of type IIA compactifications.…”

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“…One can then check that, in the above range of Imτ and ρ, (5.28) are always satisfied. That is, in this parametric regime the effective membranes and strings never become light enough to cause a breakdown of the EFT -see also [16] for a detailed discussion of energy scales in various perturbative regimes of simple concrete models.…”

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“…See e.g [30]. for a full correspondence between the KK and winding scales in toroidal compactifications of type IIA and type IIB.…”

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“…This conjecture is much stronger, because it applies to any scalar, including massive mediators, and results in very strong constraints on effective theory models containing scalars. While equation (1.1) has nice implications and seems compatible also with the swampland distance conjecture [15,17], it mixes ingredients that are clearly long-range with others that are related to short-range interactions (like the quartic couplings). Its derivation from first principles, even in simple situations, is therefore challenging.…”