# GEOMETRY, DUALITY AND STRINGS

## Description

In this workshop we will study some recent developments on the understanding of dualities in string, M- and supergravity theories. Among others, the new advancements we will discuss are: duality symmetric theories, exotic branes and non-geometric solutions, Yang-Baxter deformations, extended geometries and Janus configurations. This workshop is supported by the "Japanese Society for the Promotion of Science" and YITP.

## List of speakers

• Giuseppe Dibitetto (Uppsala University)
• Machiko Hatsuda (Juntendo & KEK)
• Noriaki Ikeda (Ritsumeikan University)
• Choi Jaewang (YITP, Kyoto University)
• Tetsuji Kimura (Keio University & Tokyo Institute of Technology)
• Taichiro Kugo (Maskawa Institute, Kyoto Sangyo University)
• Suguru Okumura(Kyoto University)
• Jeong-Hyuck Park (Sogang University)
• Minkyu Park (YITP, Kyoto University)
• Yuho Sakatani (Kyoto Prefecture University)
• Emilio Torrente-Luján (Universidad de Murcia & CERN)
• Kentaroh Yoshida (Kyoto University)

## Registration

• Registration form
• In addition to invited talks, participants can apply for 30-minute talks (please send title and abstract in the form).
• Though registration is not required to participate, it is appreciated for organisational issues.
• Registration deadline is March, 9th.
• List of participants

## Abstracts

I will first briefly review the mechanism of bubble nucleation as a possible instability channel for AdS vacua. Secondly I will discuss it in the specific context of effective supergravity model arising from string compactifications truncated to their closed string sector. By making use of positive energy theorems, I will show that such instabilities do not really occur within this setup.
Finally, I will discuss the relation between the above analysis and the weak gravity conjecture (WGC) and will eventually argue that some expected universal instabilities for non-supersymmetric AdS are crucially linked to the coupling between open and closed string sector.

#### Hatsuda, Machiko: Manifestly T-dual formulation of AdS space

In this talk the manifestly T-dual formulation is presented.
Then I will report results of its application to curved spaces such as an AdS space.
For group manifolds related by the orthogonal vielbein fields the three form H=dB in the doubled space is universal at least locally.
We construct an affine nondegenerate doubled bosonic AdS algebra to define the AdS space with the Ramond-Ramond flux.
The non-zero commutator of the left and right momenta leads to that the left momentum is in an AdS space while the right momentum is in a dS space. Dimensional reduction constraints and the physical AdS algebra are shown to preserve all the doubled coordinates.

This talk is based on arXiv:1701.06710 in collaboration with Kiyoshi Kamimura and Warren Siegel.

#### Ikeda, Noriaki: Unified picture of non-geometric fluxes and geometry of double field theory via supergeometry

We give a systematic derivation of the local expressions of the NS H-flux, geometric F- as well as non-geometric Q- and R-fluxes in terms of bivector \beta- and two-form B-potentials including vielbeins. They are obtained using a supergeometric method on QP-manifolds by twist of the standard Courant algebroid on the generalized tangent space without flux. Bianchi identities of the fluxes are easily deduced. We extend the discussion to the case of the double space and present a formulation of T-duality in terms of canonical transformations between graded symplectic manifolds. Finally, the construction is compared to the formerly introduced Poisson Courant algebroid as a model for R-flux.

#### Jaewang, Choi: Super Yang-Mills theory with position dependent coupling

When the coupling depends on the position, whether supersymmetry is preserved or not is not manifest. We found some conditions to preserve supersymmetry with position dependent coupling by deforming the N=4 SYM theory. And we got some non-trivial solutions to satisfy these conditions in some specific case.

#### Kimura, Tetsuji: Exotic branes and superconformal field theories

Exotic branes are codim-2 objects in string theory compactifications. They are related to standard branes via string duality. Since D-branes play a significant role in investigating field theories from the viewpoint of string theory, it is natural to think that exotic branes should also contribute to them. We would like to investigate brane configurations in the presence of exotic branes. By virtue of them, we may (or may not) find new superconformal field theories in lower dimensions.

TBA

#### Okumura, Suguru: Deformations of the Almheiri-Polchinski model

We study Yang-Baxter deformations of a specific 1+1 D dilaton gravity model called the Almheiri-Polchinski model. We present a deformed black hole solution and compute the Bekenstein-Hawking entropy. The entropy can also be reproduced holographically by evaluating the renormalized stress tensor on a regularized screen close to a singularity which is generated by the deformation. This work is based on the collaboration arXiv:1701.06340 with Hideki Kyono and Kentaroh Yoshida.

#### Park, Jeong-Hyuck: Double Field Theory as the Stringy Extension of General Relativity: Uroboros solution to the Dark Matter problem

Both Green-Schwarz superstring world-sheet action and IIA/IIB supergravities are better formulated in doubled-yet-gauged spacetime. Double Field Theory modifies GR at short distance and may solve the dark matter problem.

TBA

#### Sakatani, Yuho: Brane worldvolume theory based on duality symmetry

I will discuss our brane actions which are based on the geometry of the Double Field Theory or the Exceptional Field Theory. We show that our worldvolume theories are, at least classically, equivalent to various known brane theories for M-theory branes, D-branes, and so on. This talk is based on arXiv:1607.04265 in collaboration with Shozo Uehara.

#### Torrente-Lujan, Emilio: Non-Abelian Hydrodynamics: The dimensional reduction and embedding tensor approaches

Since Cho&Freund (1975) we know that the diffeormorphism group in $D=d+n$ dimensions contains d-dimensional diffeormosphisms plus n-Non-Abelian gauge transformations. This is the basis of the Scherk-Schwarz mechanism.
We present a progress report of some ongoing research about new approaches to the study of non-Abelian plasmas.
The new approach is two fold, in one case we use the dimensional reduction on a group manifold of a D-fluid neutral fluid to get a non-Abelian system at lower dimensions. In the other complementary case we study, using the embedding tensor technique, borrowed from supergravity gauged theories, all possible non-abelian deformations of a fluid system with a given field content.

The work to be presented is made in collaboration with JJ. Fernandez-Melgarejo and A. Ruiperez Vicente. It is the basis of two publications to appear, it is also related to arXiv:1605.06080.

#### Yoshida, Kentaroh: Yang-Baxter deformations and generalized supergravity

It is well-known that type IIB superstring theory on the AdS_5 x S^5 background is classically integrable. Recently, integrable deformations of this system have been studied very actively by adopting a systematic way called the Yang-Baxter deformation.

In this talk, I will give a review on recent progress on this issue. The deformations under the unimodularity condition lead to solutions of type IIB supergravity including the Lunin-Maldacena backgrounds (dual for beta deformations of the N=4 super Yang-Mills theory), the Maldacena-Russo backgrounds (dual for non-commutative gauge theories) and Schroedinger spacetimes (dual for non-relativistic conformal field theories). In general, however, the resulting deformed backgrounds are not solutions of the standard type IIB supergravity, but of the generalized supergravity. Finally I will describe the relation between noncommutative gauge theories and the generalized supergravity.

## Banquet

March 9th, 18:15 at “Sharaku” 百万遍 しゃらく (The banquet fee will be around 3000-4000 Yen, which depends on how much we eat and drink.)
https://r.gnavi.co.jp/k614100/

## Miscellanea

### Organisation

• Jose J. Fernández-Melgarejo (YITP, Kyoto University)
• Shigeki Sugimoto (YITP, Kyoto University)