Variations on Brane Supersymmetry Breaking

• Emilian Dudas

We provide new string vacua with Brane supersymmetry breaking (BSB), containing fewer open string moduli compared to the standard BSB models. They display, in addition to the untwisted NS-NS tadpoles, additional NS-NS tadpoles coming from the twisted sectors. These models are not continuously connected to the standard constructions.

Dynamical Cobordism in the absence of supersymmetry

• Andriana Makridou

The Swampland Program provides tools that can improve our understanding of quantum gravity, including non-supersymmetric string theories. The Cobordism Conjecture does not rely on the presence of supersymmetry, and serves as a guiding principle towards identifying new objects, which are defects closing off the spacetime. In this talk, I will introduce the framework of dynamical cobordism and will explain how it can be used to extract an explicit description of cobordism-predicted end-of-the-world (ETW) branes.

Misaligned SUSY in String Vacua

• Giorgio Leone

A concrete possibility for String Phenomenology consists in the study of vacua in which supersymmetry is broken at the string scale. Unfortunately such scenarios are often plagued by instabilities coming from tadpoles and perturbative corrections that modifies the background geometry. Although the fate of these vacua is not known in general, they rely on absence of tachyons in the tree level spectrum, thus being classically stable. However the situation could be much worse and indeed in literature vacua giving rise to tachyons from SUSY breaking are well known, for which any further perturbative analysis is meaningless. In this talk I will show how the sector averaged sum, a quantity encoding the global behaviour of the spectrum at large mass defined by Dienes and refined by Cribiori, Tonioni, Parameswaran and Wrase, is well suited to distinguish the two situations for closed string vacua, although not being able to describe cases in which both open and closed tachyon is projected out through an orientifold realization. A model independent proof of the previous statements along with explicit 10d examples will be provided

The Heterotic String Potential Energy

• Savdeep Sethi

Intersecting End of The World branes: an effective approach beyond SUSY

• Roberta Angius

The Dynamical Cobordism is a powerful analysis to explore infinite distance limits in the scalar field space for general theories. The method is general and it is crucially independent of supersymmetry. We describe spacetime dependent configurations in which some scalar fields reach infinite distance in the field space at finite distance in spacetime, where the metric solution hits a curvature singularity and the spacetime ends, providing a dynamical realization of the Cobordism Conjecture. At the spacetime boundary, the End of The World brane encodes the information of the corresponding infinite distance limit and allows to explore the Swampland Distance Conjecture, even in the presence of scalar potentials. We consider theories with different kinds of End of The World branes, associated to different scalars, and we study the physics at their intersection by constructing explicit local solutions. These configurations are interesting to study many different physical setups, such as the network of infinite distance limits in Calabi-Yau moduli spaces, or the collision of bubbles of nothing in cosmology.

Non-Supersymmetric Heterotic Branes

• Justin Kaidi

The common statement that any consistent quantum gravity theory contains dynamical objects with all possible charges suggests that there are still a number of hitherto-unidentified branes in string theory. In this talk I will discuss four of these new branes, focusing on heterotic string theories. The focus of the discussion will be on the relationship between these branes and the lower-dimensional vacua obtained by closed string tachyon condensation in the ten-dimensional, non-supersymmetric heterotic string theories.

The potential and the cosmological constant in non-SUSY string theory and comments on the distance conjecture

• Steven Abel

Theories with modular invariance are made finite by extreme UV/IR mixing. Finiteness then dictates that this must be the case even when supersymmetry is broken. Thus modular invariance gives us a way of thinking about the properties of non-supersymmetric strings without making any kind of assumptions about model building. In particular one can use number theoretical techniques (specifically the Rankin-Selberg-Zagier method) to extract an effective potential in terms of regulated supertraces – the equivalent of the Coleman-Weinberg potential. The understanding gained from this calculation allows us to inject several new ideas into ongoing discussions of the swampland. For example, we find that the distance conjecture can more appropriately be formulated in terms of these supertraces rather than distance scales. Using these results, we will see that there exist very general classes of modular invariant theories in which the distance conjecture holds as well as other classes in which it seems not to.

Codimension-one vacua of non-supersymmetric strings

• Salvatore Raucci

Tadpole potentials are the leading manifestation of the absence of supersymmetry in non-supersymmetric string models. A remarkable consequence is that the notion of vacuum solutions becomes puzzling. Codimension-one vacua were originally proposed as an alternative to vacuum solutions for non-supersymmetric strings, although recent investigations have indicated different interpretations in some cases. In this talk, I will review the known codimension-one vacua of non-supersymmetric strings and emphasize some of their peculiarities when interpreted as domain walls or as time-dependent backgrounds. I will also comment on T-dual models in which tadpole potentials are localized.

Automorphic Forms and Heterotic Vacua

• Nicole Righi

Heterotic toroidal orbifolds represent a powerful framework to inspect the landscape due to their modular properties. In this talk, I will review existing no-go theorems on heterotic de Sitter vacua and prove new ones for several classes of vacua, substantiating and extending previous conjectures. These theorems allow for a loophole once supersymmetry is broken: I will show the criteria that lead to metastable de Sitter vacua, also identifying the inherently stringy non-perturbative effect that break supersymmetry and potentially realise such vacua. Then, I will extend this basic setup to higher genera and show how to construct the building blocks needed to write the scalar potential and study brand new vacua.

Discussion Session

• Carlo Angelantonj & Miguel Montero