Deconstructing the String Landscape (a.k.a. landscapia)

29 nov. 2023, 09:00 → 1 déc. 2023, 18:00 Europe/Paris

Amphitheater Claude Bloch (IPhT, CEA/Saclay, France)

Despite its uniqueness, string theory has a “landscape” of low-energy solutions with very different observable physics: different cosmological constants, matter content and interactions.             

The goal of the conference is to bring together part of the community of researchers working on of string compactifications and their relation with a series of topics such as moduli stabilisation, non-supersymmetric vacua, de Sitter constructions, scale separation, non-geometric backgrounds and particle model building.

This event will be preceded by the String-Cosmo day, on the 28th of November at the APC, in central Paris. 

Recordings and slides for the review and research talks can be found in the "detailed view" of the Timetable

Organizers: Mariana Graña, Alvaro Herraez and Nicolas Kovensky    

Review talks:

Jim Halverson (machine learning for the landscape)            
Severin Lüst (de Sitter vacua)            
Miguel Montero (string universality and classification of string vacua)            
Thomas Van Riet (moduli stabilisation, scale separation)            
 

Discussion sessions:

Moduli stabilisation.          
Moderators: Iosif Bena, Sven Krippendorf, Erik Plauschinn, Daniel Waldram       

Scale separation and holography.         
Moderators: Eric Perlmutter, Irene Valenzuela, Thomas Van Riet           

Perspectives for Particle physics.         
Moderators: Luis Ibáñez, Andre Lukas, Fernando Quevedo, Fabian Ruehle   

De Sitter vacua and beyond.         
Moderators: David Andriot, Ralph Blumenhagen, Gary Shiu, Radu Tatar     

String universality and classification of string vacua.         
Moderators: Anamaría Font, Jonathan Heckman, Alessandro Tomasiello, Timo Weigand      

Non-geometric and non-supersymmetric backgrounds.         
Moderators: Carlo Angelantonj, Emilian Dudas, Chris Hull, Ilarion Melnikov         
 

Research talks:     
Nathan Brady     
José Calderón-Infante       
Peng Cheng       
Niccolò Cribiori      
G. Bruno De Luca      
Markus Dierigl      
Dan Israel      
Magdalena Larfors      
Jakob Moritz     
Susha Parameswaran      
Héctor Parra De Freitas      
Salvatore Raucci      
Anindya Sengupta  
Houri Christina Tarazi      
Max Wiesner  

 

 

            

mer. 29 novembre

Registration & Welcome Coffee

Opening Remarks

Review Talk: Moduli Stabilization, Scale Separation and Holography

Président de session: Thomas Van Riet

1 Moduli Stabilization, Scale Separation and Holography

Orateur: Thomas Van Riet

slides.pdf

Talk

:: De Sitter vacua at leading order

Président de session: Jakob Moritz

2 De Sitter vacua at leading order

In this talk I will present the first explicit examples of de Sitter vacua as envisioned by Kachru, Kallosh, Linde and Trivedi 20 years ago, in the tree level approximation in both the string loop and $\alpha’$ expansion. I will begin by summarizing the construction of all the relevant components, from Calabi-Yau orientifolds, and a mechanism to generate exponentially small superpotentials from quantized fluxes, to the explicit stabilization of hundreds K\”ahler moduli via non-perturbative D3-instantons on cycles that satisfy Witten’s rigidity conditions, and the construction of warped Randall-Sundrum throats that can host SUSY breaking uplifts. Genuinely $\mathcal{N}=1$ corrections in the $\alpha’$ and $g_s$ expansions are potentially important but are not fully known, and I will comment on robustness against these.

Orateur: Jakob Moritz

slides.pdf

Talk

11:30 Coffee Break

Discussion Session: Moduli Stabilization

Présidents de session: Dan Waldram, Erik Plauschinn, Iosif Bena, Sven Krippendorf

3 Discussion Session: Moduli Stabilization

Orateurs: Iosif Bena, Sven Krippendorf, Erik Plauschinn, Dan Waldram

13:15 Lunch Break

:: Exploring the Interior of N=1 Field Spaces

Président de session: Max Wiesner

4 Exploring the Interior of N=1 Field Spaces

To study realistic vacua of string theory with minimal or no supersymmetry it is crucial to have a good understanding of the field space of such theories away from asymptotic boundaries where all supersymmetry breaking effects are diluted. In this talk I will focus on four-dimensional theories arising from F-theory compactifications on elliptically-fibered Calabi-Yau fourfolds X4: T2 —> B3. In this case all supersymmetry breaking effects are diluted in the limit of large volume for B3 where the field space is well-described by the classical expressions inherited from theories with N=2 supersymmetry. I will study corrections to the field space geometry away from such limits. A particular focus lies on regimes in field space where curves intersected by the anti-canonical class of B3 become small for which I show that the structure of the field space is significantly altered from the naive N=2 expectation due to genuine N=1 effects. Furthermore I will show that the mixing between Kahler and complex structure moduli is generically expected to significantly affect the field space structure in asymptotic limits in the complex structure field space of X4 for any finite value of the volume of B3.

Orateur: Max Wiesner

slides.pdf

Talk

:: (De)Constructing Scale Separation with Weak Gravity and Anisotropies

Président de session: Niccolò Cribiori

5 (De)Constructing Scale Separation with Weak Gravity and Anisotropies

The existence of a separation of scales between the four observed spacetime dimensions and the unobserved additional ones is a minimal requirement for string phenomenology and an open problem therein. In the first part of the talk, I will present a general argument excluding scale separation in anti-de Sitter vacua of gauged supergravity with at least eight supercharges, as a consequence of the weak gravity conjecture. The argument is evaded by vacua with four or less supercharges and indeed examples of this kind are known in type IIA compactifications. In the second part, I will review one of these constructions and comment on some of its features, such as the fact that the internal manifold needs to be non-isotropic to get scale separation. This motivates the need to look for anisotropic setups more in general.

Orateur: Niccolò Cribiori

slides.pdf

Talk

:: Tadpole and Moduli in Type IIB on the 1^9 Landau-Ginzburg Model

Présidents de session: Nathan Brady, Anindya Sengupta

6 Tadpole and Moduli in Type IIB on the 1^9 Landau-Ginzburg Model

We report recent progress made on flux backgrounds of type IIB string theory on 4D Minkowski times a non-geometric internal manifold characterized by its worldsheet description in terms of the 1^9 Landau-Ginzburg model. We present a classification of solutions, the minimum flux tadpole attained by each class, and the number of massive complex structure moduli for the minimum-tadpole configurations. We also present a solution of the shortest vector problem in the lattice of supersymmetric flux backgrounds in this model.

Orateurs: Nathan Brady, Anindya Sengupta

slides.pdf

Talk

15:45 Coffee Break

:: HS Symmetry at Infinite Distances and its Stringy Origin

Président de session: José Calderón-Infante

7 HS Symmetry at Infinite Distances and its Stringy Origin

In the first part of this talk, I will sketch a proof for the first part of the CFT Distance Conjecture, which states that higher-spin symmetry must always lie at infinite distance in the conformal manifold of any local CFT in more than two dimensions. In the second part, I will address the stringy origin of these HS symmetries. Among other things, I will discuss a remarkable connection between no scale separation and the Sharpened Distance Conjecture.

Orateur: José Calderón-Infante

slides.pdf

Talk

Discussion Session: Scale Separation and Holography

Présidents de session: Eric Perlmutter, Irene Valenzuela, Thomas Van Riet

8 Discussion Session: Scale Separation and Holography

Orateurs: Eric Perlmutter, Irene Valenzuela, Thomas Van Riet

18:15 Wine & Cheese Reception

jeu. 30 novembre

09:30 Welcome Coffee

Review Talk: Machine Learning for the Landscape

Président de session: Jim Halverson

9 Machine Learning for the Landscape

Orateur: Jim Halverson

slides.pdf

Talk

:: Machine-learning Calabi-Yau metrics

Président de session: Magdalena Larfors

10 Machine-learning Calabi-Yau metrics

Calabi Yau (CY) manifolds are used ubiquitously in research on string theory. Since decades, these spaces have provided the main avenue to connect string theory with observable physics. A stumbling block in these constructions is the lack of an analytical expression for the CY metrics. In this talk I will review recent work on obtaining numerical approximations of CY metrics using machine learning, and the prospects such metrics may have in furthering string theory research.

Orateur: Magdalena Larfors

slides.pdf

Talk

11:30 Coffee Break

Discussion Session: Perspectives on Particle Physics

Présidents de session: Luis Ibáñez, Andre Lukas, Fernando Quevedo, Fabian Ruehle

11 Discussion Session: Perspectives on Particle Physics

Orateurs: Luis Ibáñez, Andre Lukas, Fernando Quevedo, Fabian Ruehle

13:15 Lunch Break

Review Talk: De Sitter vacua and Beyond

Président de session: Severin Lüst

12 De Sitter vacua and beyond

Orateur: Severin Lüst

slides.pdf

Talk

:: A dS from higher dimensions

Président de session: G. Bruno De Luca

13 A dS from higher dimensions

Constructing realistic vacua in UV-complete theories of gravity remains a challenging open problem.
In the context of gravity compactifications, quantum effects provide mechanisms to stabilize internal spaces with zero or negative curvature, thereby enlarging the set of geometries that can be employed to construct realistic physical models.
Specifically, I will describe how the inclusion of Casimir energy in the internal space evades general constraints and leads to scale-separated AdS and de Sitter vacua in M-theory.

Orateur: G. Bruno De Luca

slides.pdf

Talk

15:45 Coffee Break

:: Transient de Sitter vacua via interacting Dark Sectors

Président de session: Susha Parameswaran

14 Transient de Sitter vacua via interacting Dark Sectors

I will discuss how interacting Dark Sectors can give rise to transient de Sitter vacua, starting from hilltop or runaway potentials, which are consistent with cosmological observations and the Swampland Conjectures.

Orateur: Susha Parameswaran

slides.pdf

Talk

Discussion Session: De Sitter and Beyond

Présidents de session: David Andriot, Ralph Blumenhagen, Gary Shiu, Radu Tatar

15 Discussion Session: De Sitter and Beyond

Orateurs: David Andriot, Ralph Blumenhagen, Gary Shiu, Radu Tatar

20:00 Workshop Dinner: Restaurant La Contre Allée

La Contre Allée
83 Av. Denfert Rochereau, Paris.
RER station: Denfert Rochereau

ven. 1 décembre

09:30 Welcome Coffee

Review Talk: String universality and classification of string vacua

Président de session: Miguel Montero

16 String universality and classification of string vacua

Orateur: Miguel Montero

slides.pdf

Talk

:: String universality and mixed anomalies

Président de session: Markus Dierigl

17 String universality and mixed anomalies

In this talk I will summarize recent advances in string universality utilizing the absence of certain mixed anomalies. These anomalies in general contain contributions from the higher-from symmetries of the theory and impose severe consistency conditions on the gauge sectors, in particular the global form of the gauge group. Interestingly, many of these low-energy conditions allow for geometric interpretations and hint at the corresponding UV completion in string theory.

Orateur: Markus Dierigl

slides.pdf

Talk

11:30 Coffee Break

:: Supersymmetric string vacua with flat backgrounds

Président de session: Peng Cheng

18 Supersymmetric string vacua with flat backgrounds

In this talk, we will focus on some examples to discuss the effects of flat backgrounds on supersymmetric string vacua with both 16 and 8 supercharges.

Orateur: Peng Cheng

slides.pdf

Talk

Discussion Session: String universality and classification of string vacua

Présidents de session: Alessandro Tomasiello, Anamaría Font, Jonathan Heckman, Timo Weigand

19 Discussion Session: String universality and classification of string vacua

Orateurs: Anamaría Font, Jonathan Heckman, Alessandro Tomasiello, Timo Weigand

13:30 Lunch Break

:: On the Exotic String Landscape

Président de session: Houri Christina Tarazi

20 On the Exotic String Landscape

Non geometric string constructions can give us a window into interesting corners of the quantum gravity landscape and enlarge the boundaries of our current understanding. I will firstly be discussing such constructions in 8 supercharges where the usual prominent compactifications arise from Calabi-Yau threefolds. Such compactifications always come with a dilation field controlling the volume of the threefold. However, using asymmetric orbifold constructions we will find theories with no hypermultiplets in 4 or 5 dimensions and no neutral hypers in 6d. We argue that these theories can also be obtained by going to strong coupling/small volume regions of geometric constructions where a new Coulomb branch opens up and moving in this direction freezes the volume/string coupling constant. Interestingly we find that the Kodaira condition encountered in geometric limits of F-theory compactifications to 6 dimensions is violated in these corners of the landscape due to strong quantum corrections.
I will then move on to more exotic orbifold constructions using symmetries of the string lattice that are not automorphisms of the target torus known as quasicrystalline compactifications.

Orateur: Houri Christina Tarazi

slides.pdf

Talk

:: Non-supersymmetric strings and rank reduction

Président de session: Héctor Parra De Freitas

21 Non-supersymmetric strings and rank reduction

The landscape of string vacua with 16 supercharges consists of various disconnected components which are nevertheless interrelated through maps taking on very different forms depending on the duality frame employed. These include asymmetric orbifolds on both the heterotic and type II sides, and frozen singularities in the F-theory and M-theory pictures. In this talk I will consider the non-supersymmetric cousins of the heterotic asymmetric orbifolds which are realized a la Scherk-Schwarz, i.e. by including (-1)^F factors in the orbifold. I will discuss their classification and on certain structures surviving supersymmetry breaking which involve their gauge symmetry enhancement. I will also comment on the problem of mapping the maximal rank component to those of reduced rank and certain associated puzzles which also involve non-supersymmetric compactifications of type II strings.

Orateur: Héctor Parra De Freitas

slides.pdf

Talk

:: Deconstructing heterotic flux vacua

Président de session: Dan Israel

22 Deconstructing heterotic flux vacua

We investigate the interrelation between topology and Narain T-duality of heterotic flux vacua. We present evidence that all 5 and 4-dimensional Minkowski space heterotic flux backgrounds with 8 supercharges have a locus in the moduli space with a T-dual description in terms of a compactification on the product of a K3 surface with a circle or a torus. We examine the implications of these dualities for CHL-like orbifolds that reduce the rank of the gauge group, as well as those that lead to minimal supersymmetry in 4 dimensions. We also discuss properties of flux vacua that preserve minimal supersymmetry in 4 dimensions that cannot be related to conventional compactifications by Narain T-duality.

Orateur: Dan Israel

slides.pdf

Talk

16:00 Coffee Break

:: Charting the landscape of non-supersymmetric strings

Président de session: Salvatore Raucci

23 Charting the landscape of non-supersymmetric strings

The landscape of non-supersymmetric string theories remains largely uncharted. Standard techniques from flux compactifications are lost, forcing us to fall back on the full string equations of motion. Despite this, non-supersymmetric strings are the simplest arena in which we can capture the effects of the absence of supersymmetry from complete UV descriptions. In this talk, I will discuss Freund-Rubin solutions of these models, based on R-R, NS-NS, and gauge fluxes, and examine why it is challenging to find more complex vacua with the available technology. I will show that the fake supersymmetry formalism could offer a way forward.

Orateur: Salvatore Raucci

slides.pdf

Talk

Discussion Session: Non-geometric and non-supersymmetric backgrounds

Présidents de session: Carlo Angelantonj, Emilian Dudas, Chris Hull, Ilarion Melnikov

24 Discussion Session: Non-geometric and non-supersymmetric backgrounds

Orateurs: Carlo Angelantonj, Emilian Dudas, Chris Hull