String Phenomenology 2023

Session

Parallel

4 Jul 2023, 14:00

Institute for Basic Science, Daejeon

Conveners

Parallel: Tue 1-B

• Jonathan Heckman

Parallel: Tue 2-B

• Alexander Westphal

Parallel: Thu 1-B

• Jakob Moritz

Parallel: Thu 2-B

• Jai-chan Hwang

58. Reflection 7-branes and how to use them

Markus Dierigl

04/07/2023, 14:00

In this talk we argue for the existence of a non-supersymmetric 7-brane in type IIB superstring theory predicted by the Cobordism Conjecture. We also investigate their localized dynamics in terms of worldvolume fields as well as their role as charge conjugation operators.

59. The Branes Behind Generalized Symmetry Operators

Max Huebner

04/07/2023, 14:15

By now it is well-known that the global symmetries of a quantum field theory (QFT) can be recast as the existence of certain extended topological operators. This reformulation has produced much progress in expanding the notion of symmetry, culminating in so-called categorical or generalized global symmetries. We review a systematic, non-Lagrangian construction of such symmetry operators for...

60. Back to Heterotic Little String Theories on ALE Spaces

Muyang Liu

04/07/2023, 14:30

I will revisit some aspects of Heterotic little strings on ALE spaces motivated by recent advances in understanding the structures of six-dimensional theories and their continuous 2-group symmetries. In particular, the construction of novel Heterotic E8 × E8 ALE instantonic theories through the 6d conformal matter approach are presented and therefore extend previous results explored by...

61. Geometric Bounds on the 1-Form Gauge Sector

Paul-Konstantin Oehlmann

04/07/2023, 14:45

6D SUGRA theories give an interesting testing ground of our understanding of field theory condition and geometric String Landscape searches.
In this talk I discuss how we bound the global gauge group topology in 6D SUGRAs coupled to non-Abelian gauge symmetries which is dictated by a perturbative heterotic string. This allows to geometrically deduce, that the global gauge group topology must...

62. Towards a complete classification of 6D supergravities

Gregory Loges

04/07/2023, 15:00

The structure of 6D supergravity is very rigid; for example, supersymmetry and anomaly cancellation greatly constrain the possible choices for gauge group and matter content. The task of constructing consistent theories can be rephrased in terms of finding cliques with certain desirable properties in a multigraph built from simple building blocks. In this talk I will outline this strategy for...

63. Aspects of string theory compactifications with non trivial torsional homology

Matteo Zatti

04/07/2023, 15:15

The concept of integer homology naturally arises in string theory compactifications to implement flux quantization conditions. However, only the free part is usually considered. We recently discovered that if torsional homology is considered, a new natural interpretation of some massive KK modes with mass much lower than the KK scale arises. Using such description, we found that in some type 2...

64. The cosmological constant is probably still zero

Antonio Padilla

04/07/2023, 16:00

We consider a wide class of four-dimensional effective field theories in which gravity is coupled to multiple four-forms and their dual scalar fields, with membrane sources charged under the corresponding three-form potentials. Four-form flux, quantised in units of the membrane charges, generically generates a landscape of vacua with a range of values for the cosmological constant that is...

65. Smearing and Unsmearing KKLT AdS Vacua

Nicolas Kovensky

04/07/2023, 16:15

Gaugino condensation on D-branes wrapping internal cycles gives a mechanism
to stabilize the associated moduli. According to the effective field theory, this gives rise,
when combined with fluxes, to supersymmetric AdS4 solutions. We provide an approximate ten-dimensional description of these vacua. More precisely find the supersymmetry equations for type II AdS4 vacua with gaugino...

66. Smearing and Unsmearing KKLT AdS Vacua Part II

Dimitrios Toulikas

04/07/2023, 16:30

In the framework of generalized complex geometry, we solve the supersymmetry equations for type IIB AdS4 vacua with gaugino condensates on smeared D7-branes. We show that supersymmetry requires a (conformal) Calabi-Yau manifold and imaginary self-dual three-form fluxes with an additional (0,3) component. The latter is proportional to the cosmological constant, whose magnitude is determined by...

67. Fayet-Iliopoulos D-Term in Non-Supersymmetric Heterotic String Orbifolds

Alonzo Rodrigo Diaz Avalos

04/07/2023, 16:45

The Fayet–Illiopoulos D–term is a common feature in N = 1 string vacua that contain an anomalous U(1) gauge symmetry, and arises from a one–loop diagram in string perturbation theory. The same diagram is generated in string vacua in which supersymmetry is broken directly at the string scale, either via spontaneous Scherk– Schwarz breaking, in which case the gravitino mass is determined by the...

68. Interpolation and cosmological constant in non-susy heterotic strings

Yuichi Koga

04/07/2023, 17:00

We study d-dimensionally compactified non-susy heterotic string models, including interpolating models with the arbitrary number of freely acting Z_2 twisted directions. Taking the limits of the compactified radii to zero and infinity, we show some examples of the various interpolation patterns in the d=2 (8-dimensional) case. In the region where supersymmetry is asymptotically restored, we...

69. Life-time of Metastable Vacuum in String Theory and Trans-Planckian Censorship Conjecture

Sohei Tsukahara

04/07/2023, 17:15

We investigate the catalytic effect on the decay of a metastable vacuum in type IIB string theory. The decay bubble forms a bound state with an impurity, acting as a catalyst due to the non-linear DBI action. The vacuum's lifetime is calculated beyond the WKB approximation, and it satisfies the Trans-Planckian Censorship Conjecture (TCC) if the string scale is sufficiently smaller than the...

95. No Asymptotic Acceleration without Higher-Dimensional de Sitter Vacua

Gerben Venken

06/07/2023, 14:00

There has recently been considerable interest in the question whether and under which conditions accelerated cosmological expansion can arise in the asymptotic regions of field space of a d-dimensional EFT. In this talk I will present a conjecture that such acceleration is impossible unless there exist metastable de Sitter vacua in more than d dimensions. That is, `Asymptotic Acceleration...

96. Number Theory and the Road to Heterotic Vacua

Nicole Righi

06/07/2023, 14:15

Heterotic toroidal orbifolds represent a powerful framework to inspect the landscape due to their modular properties. In this talk, I will extend the basic SL(2,Z)-symmetric setup to higher genera modular groups, and show how to construct the building blocks needed to compute the scalar potential and study brand new vacua.

97. Challenges and new perspectives on dS vacua

Simon Schreyer

06/07/2023, 14:30

In this talk I will discuss recently discovered challenges for dS vacua in the Large Volume Scenario and the anti-D3-brane uplift. In particular, I will discuss the effect of $\alpha'$ corrections on the metastability condition of the NS5-brane at the tip of a the Klebanov-Strassler throat which is crucial for the anti-D3-brane uplift. Thereby, we will discover how $\alpha'$ corrections to...

98. Characterizing negative scalar potentials: an Anti-Trans-Planckian Censorship Conjecture

Ludwig Horer

06/07/2023, 14:45

While positive scalar potentials have been extensively studied in effective string theories, in this talk I will discuss properties of negative potentials. This is accomplished by an Anti-Trans-Planckian Censorship Conjecture (ATCC), inspired by a refinement of the TCC. The ATCC states that in a contracting universe, modes that become sub-Planckian in length violate the validity of the...

99. Perturbative de Sitter and Brane Inflation

Mario Ramos Hamud

06/07/2023, 15:00

RG-induced moduli stabilisation was recently proposed as a new mechanism that adapts to string theory a perturbative method for stabilising moduli without leaving the domain of perturbative control and without the inclusion of non-perturbative effects. In this talk, we briefly revise the necessary ingredients in the construction of this mechanism. In addition, we examine the cosmological...

100. Sharpening the boundaries between flux landscape and Swampland by tadpole charge

Keiya Ishiguro

06/07/2023, 15:15

There is a candidate of string compactification background that has no Kähler moduli, which is the mirror of the rigid Calabi-Yau threefold. We studied Type IIB flux compactifications on the mirror space, corresponding to a T-dual of the DeWolfe-Giryavets-Kachru-Taylor model in Type IIA flux compactifications. The lack of Kähler deformations suggests it can be a suitable space for learning...

101. Perturbations in O(D,D) string cosmology

Stephen Angus

06/07/2023, 16:00

Tensions in cosmology may be addressed by modifying our theory of gravity. String theory at low energies contains additional fields that are not present in general relativity but are naturally embedded in the O(D,D)-symmetric framework of double field theory (DFT). Moreover, the O(D,D) symmetry uniquely prescribes the interactions between the extended gravitational sector and other matter,...

102. Progress in constructing KKLT de Sitter vacua

Andreas Schachner

06/07/2023, 16:15

I present type IIB Calabi-Yau orientifold flux compactifications that contain all the necessary components of KKLT de Sitter vacua. Specifically, I exhibit 4-dimensional SUSY AdS vacua featuring conifold regions and small values of the superpotential, in which all moduli, including Kähler moduli, are stabilised in a controlled way. In these vacua the inclusion of a single anti-D3 brane makes...

103. Late-time accelerating cosmologies

Flavio Tonioni

06/07/2023, 16:30

I will characterize the late-time expansion rate of the universe in multi-scalar cosmologies with multi-exponential potentials, taking advantage of previously unobserved universal asymptotic features of the solutions to the cosmological equations. This provides a simple diagnostic of whether any given multi-exponential potential holds the necessary conditions for late-time cosmic acceleration....

120. Cosmic Acceleration and Turns in the Swampland

Guoen Nian

06/07/2023, 16:45

We argue that field trajectories, which lead to cosmic acceleration and feature rapid turns near the boundary of the moduli space, are in the Swampland. We obtain this result by assuming the validity of the Swampland Distance Conjecture (SDC) in the presence of a positive (nearly-flat) scalar potential and by focusing on hyperbolic spaces, as prototype geometries of infinite distance limits of...

105. Implications of the gravitino mass/distance conjecture on inflation

Takahiro Terada

06/07/2023, 17:00

The gravitino mass/distance conjecture states that an infinite tower of particles arises in the (large distance) limit of vanishing gravitino mass. An application of the conjecture to an inflationary spacetime gives us a lower bound on the gravitino mass in terms of the Hubble parameter whereas the requirement of positive inflationary energy and the structure of the supergravity potential...

106. Kination in String Theory

Filippo Revello

06/07/2023, 17:15

I will discuss some theoretical and phenomenological implications of a string theory-inspired, cosmological phase of kination, dominated by the kinetic energy of a rapidly rolling scalar. In the first part of the talk, I will describe how such a kination epoch can naturally arise in string compactifications after inflation, focusing on the case where it is driven by the volume modulus. I will...

107. A Boltzmann equation approach to string thermodynamics

Gonzalo Villa

06/07/2023, 17:30

Using interaction rates computed to second order in string perturbation theory, we pose a system of Boltzmann equations describing an ensemble of long open and closed strings in different regimes (which include high and low density of D-branes), for an arbitrary number of "effectively non-compact" directions, along which strings cannot wind. We find equilibrium distributions for all these...