# Schedule for: 17w5018 - String and M-theory geometries: Double Field Theory, Exceptional Field Theory and their Applications

Beginning on Sunday, January 22 and ending Friday January 27, 2017

All times in Banff, Alberta time, MST (UTC-7).

Sunday, January 22 | |
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16:00 - 17:30 | Check-in begins at 16:00 on Sunday and is open 24 hours (Front Desk - Professional Development Centre) |

17:30 - 19:30 |
Dinner ↓ A buffet dinner is served daily between 5:30pm and 7:30pm in the Vistas Dining Room, the top floor of the Sally Borden Building. (Vistas Dining Room) |

20:00 - 22:00 | Informal gathering (Corbett Hall Lounge (CH 2110)) |

Monday, January 23 | |
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07:00 - 08:45 |
Breakfast ↓ Breakfast is served daily between 7 and 9am in the Vistas Dining Room, the top floor of the Sally Borden Building. (Vistas Dining Room) |

08:45 - 09:00 | Introduction and Welcome by BIRS Station Manager (TCPL 201) |

09:00 - 10:00 |
Olaf Hohm: Background Independence vs. Duality Invariance at Order alpha' ↓ I show that in bosonic string theory there is a conflict at
first order in alpha' between manifest background independence and
manifest T-duality invariance in terms of the standard massless fields,
metric, b-field and dilaton. A double field theory formulation
of the bosonic string nevertheless exists in terms of an
\alpha'-deformed frame or vielbein formalism. (TCPL 201) |

10:00 - 10:30 | Coffee Break (TCPL Foyer) |

10:30 - 11:30 |
Diego Marqués: The Odd story of alpha-prime corrections ↓ I will review higher-derivative extensions of Double Field Theories that encompass the first order corrections to the heterotic and bosonic strings in a unified framework. I will then explore applications of the formalism, with emphasis on how to compute higher-derivative corrections to gauged supergravities through generalized Scherk-Schwarz compactifications. (TCPL 201) |

11:30 - 13:00 | Lunch (Vistas Dining Room) |

13:00 - 14:00 |
Guided Tour of The Banff Centre ↓ Meet in the Corbett Hall Lounge for a guided tour of The Banff Centre campus. (Corbett Hall Lounge (CH 2110)) |

14:00 - 14:20 |
Group Photo ↓ Meet in foyer of TCPL to participate in the BIRS group photo. The photograph will be taken outdoors, so dress appropriately for the weather. Please don't be late, or you might not be in the official group photo! (TCPL Foyer) |

14:30 - 15:30 |
Jeong-Hyuck Park: Green-Schwarz superstring and Stringy Gravity in doubled-yet-gauged spacetime ↓ World-sheet superstring and target-spacetime supergravities have been fully reformulated and generalized in doubled-yet-gauged coordinates. DFT appears as a string theory extension of, and possibly an alternative to, Einstein gravity. I will review my related recent works (1606.09307, 1609.04265), which in particular includes a `uroboros' solution to the dark matter problem. (TCPL 201) |

15:30 - 16:00 | Coffee Break (TCPL Foyer) |

16:00 - 17:00 |
Igor Bandos: Underlying 11D EFT: A conjecture ↓ Recently proposed exceptional field theories (EFTs) making
manifest the duality $E_{n(n)}$ symmetry, first observed as
nonlinearly realized symmetries of the maximal $d=3,4,...,9$
supergravity ($n=11-d$) and containing 11D and type IIB supergravity
as sectors, were formulated in enlarged spacetimes. In the case of
$E_{7(7)}$ EFT such an enlarged spacetime can be identified with the
bosonic body of the $d=4$ central charge superspace
$\Sigma^{(60|32)}$, the ${\cal N}=8$ $d=4$ superspace completed by
56 additional bosonic coordinates associated to central charges of the
maximal $d=4$ supersymmetry algebra.
In this talk we show how the hypothesis on the relation of all
the known $E_{n(n)}$ EFTs, inclusing $n=8$, with supersymmetry leads
to the conjecture on existence of 11D exceptional field theory
living in 11D tensorial central charge superspace $\Sigma^{(528|32)}$
and underlying all the $E_{n(n)}$ EFTs with $n=2,...,8$, and probably
the double field theory (DFT). We conjecture the possible form of the
section conditions of such an 11D EFT and show that quite generic
solutions of these can be generated by superparticle models the ground
states of which preserve from one half to all but one supersymmetry.
The properties of these superparticle models are briefly discussed. We
argue that, upon quantization, their quantum states should describe
free massless non-conformal higher spin fields in D=11. (TCPL 201) |

17:30 - 19:30 |
Dinner ↓ A buffet dinner is served daily between 5:30pm and 7:30pm in the Vistas Dining Room, the top floor of the Sally Borden Building. (Vistas Dining Room) |

Tuesday, January 24 | |
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07:00 - 09:00 | Breakfast (Vistas Dining Room) |

09:00 - 10:00 | Jakob Palmkvist: Generalised Cartan superalgebras and exceptional geometry (TCPL 202) |

10:00 - 10:30 | Coffee Break (TCPL Foyer) |

10:30 - 11:30 |
Kanghoon Lee: Effective Action for Non-Geometric Fluxes from Duality Covariant Actions ↓ DFT/EFT are known to be reduced to the standard descriptions by introducing appropriately parameterized generalized metric and by applying suitably chosen section conditions. We generalize this development to non-geometric backgrounds by utilizing dual fields pertinent to non-geometric fluxes. We introduce different parameterizations for the generalized metric, in terms of the conventional supergravity fields or the dual fields. Under certain simplifying assumptions, we construct new effective action for non-geometric backgrounds. We then obtain the non-geometric backgrounds sourced by exotic branes. From them, we construct their U-duality monodromy matrices. The charge of exotic branes obtained from these monodromy matrices agrees perfectly with the charge obtained from the non-geometric flux integral. (TCPL 202) |

11:30 - 13:00 | Lunch (Vistas Dining Room) |

13:00 - 14:00 |
Daniel Waldram: Generalised geometry and marginal deformations ↓ We discuss the explicit map between marginal deformations of generic N=1, d=4 SCFTs and structures in exceptional generalised geometry that describe supersymmetric AdS backgrounds in both 11-dimensinal and type IIB supergravity. (TCPL 201) |

14:00 - 15:00 |
Charles Strickland-Constable: Supersymmetric backgrounds and generalised special holonomy ↓ It is well known that, in the absence of internal fluxes, supersymmetric Minkowski backgrounds are given by manifolds with special Riemannian holonomy, such as the celebrated Calabi-Yau spaces. I will present recent work showing that general supersymmetric Minkowski flux backgrounds are precisely the analogues of these in generalised geometry. The generalised holonomy group is simply the natural stabiliser group of the Killing spinors, and depends only on the dimension and the number of preserved supersymmetries. The Killing superalgebra, which has a neat manifestation in this language, plays a key role in the proof of the main result for N > 2 supersymmetry and we are able to fix its form explicitly using this technology. (TCPL 201) |

15:00 - 15:30 | Coffee Break (TCPL Foyer) |

15:30 - 16:30 |
Marco Gualtieri: The mathematical meaning of the generalized Kahler potential ↓ Recent advances have made it possible to finally understand the physicists' concept of generalized Kahler potential in precise mathematical terms. I will describe how this can be done once we understand the notion of symplectic Morita equivalence between Poisson manifolds. Another benefit of the study is a new formalism for thinking of generalized Kahler geometry as a whole. (TCPL 201) |

17:30 - 19:30 | Dinner (Vistas Dining Room) |

Wednesday, January 25 | |
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07:00 - 09:00 | Breakfast (Vistas Dining Room) |

09:00 - 10:00 |
Jose Alejandro Rosabal Rodriguez: Unusual vacuum choice and T duality in string theory. ↓ Based on a diferent vacuum choice we construct, using the old and the new covariant quantization, the world sheet version of the HZS double field theory. We compute the scatering amplitude of n-massless scalars and the one loop partition function. A new interpretation is given to this string theory. We also point out the relation with the ambitwistor string as the tensionless limit version of this string theory. (TCPL 202) |

10:00 - 10:30 | Coffee Break (TCPL Foyer) |

10:30 - 11:30 |
Robert Brandenberger: Why Double Field Theory might be useful in Early Universe Cosmology ↓ Why Double Field Theory might be useful in Early Universe Cosmology.... (TCPL 202) |

11:30 - 13:30 | Lunch (Vistas Dining Room) |

13:30 - 17:30 | Free Afternoon (Banff National Park) |

17:30 - 19:00 | Dinner (Vistas Dining Room) |

19:00 - 20:00 |
Emanuel Malek: Half-maximal consistent truncations using EFT and the M-theory / heterotic duality ↓ One of the most powerful applications of exceptional and double field theories has been in the study of consistent truncations via generalised Scherk-Schwarz reductions which preserve all supersymmetries. In this talk I will show how to generalise the Scherk-Schwarz procedure to define consistent truncations which break half the supersymmetries. This allows for the study of exceptional field theories on CY-surfaces and their torsion-full counterparts. Finally, I will discuss how one can use the truncation procedure to reduce exceptional field theory to heterotic double field theory, corresponding to the heterotic / M-theory duality. (TCPL 201) |

Thursday, January 26 | |
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07:00 - 09:00 | Breakfast (Vistas Dining Room) |

09:00 - 10:00 |
Chris Blair: Doubled and negative strings ↓ A key feature of string theory which can be understood naturally in DFT is the presence of exotic branes (or T-folds), for instance the 5_2^2 which is obtained by two T-dualities from the NS5 brane. The electric dual of this exotic brane can be identified with a ``negative string'' solution obtained by dualising the worldvolume directions -- including time -- of the fundamental string supergravity solution. It has been recently argued by Dijkgraaf et al that such negative branes can be understood as being surrounded by a ``bubble'' in which physics is described by various exotic string theories originally considered by Hull. Focusing on the negative string solution, I will discuss the DFT description of such exotic objects, including writing down a novel variant of DFT which applies in theories where fundamental strings are Euclidean. (TCPL 202) |

10:00 - 10:30 | Coffee Break (TCPL Foyer) |

10:30 - 11:30 |
Henning Samtleben: Applications of Exceptional Field Theory ↓ Exceptional field theories are manifestly duality covariant formulations of supergravity that have proven powerful in addressing various problems in supergravity theories. Among their applications I discuss consistent truncations of (super)gravity, higher dimensional origins of dyonic gauged supergravities, and generalised type II supergravity. (TCPL 202) |

11:30 - 13:30 | Lunch (Vistas Dining Room) |

13:30 - 17:30 | fee discussion time (TCPL 202) |

15:00 - 15:30 | Coffee Break (TCPL Foyer) |

17:30 - 19:00 | Dinner (Vistas Dining Room) |

19:00 - 20:00 |
Felix Rudolph: A Connection for Born geometry and its application to DFT ↓ A doubled space which in addition to a neutral metric \eta and a generalized metric H contains a symplectic structure \omega has been dubbed a Born geometry. We construct the unique and fully determined connection compatible with these three objects and vanishing generalized torsion. The latter is related to an integrability condition on the structures of the doubled space. Double Field Theory can be seen as a limit of Born geometry where the symplectic form is constant. Hence the Born connection provides a unique connection for DFT. (TCPL 202) |

20:00 - 21:00 |
David Berman: Open problems in DFT and EFT- a discussion ↓ I will set out a list of open problems in the area and the various different approaches people have taken. The session will then be open for participants to contribute further problems, ideas, research directions and solutions. (TCPL 201) |

Friday, January 27 | |
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07:00 - 09:00 | Breakfast (Vistas Dining Room) |

09:00 - 10:00 | Martin Cederwall: E_9 geometry (TCPL 201) |

10:00 - 10:30 | Coffee Break (TCPL Foyer) |

10:30 - 11:30 | Chris Hull: The geometry and non-geometry of double field theory (TCPL 201) |

11:30 - 12:00 |
Checkout by Noon ↓ 5-day workshop participants are welcome to use BIRS facilities (BIRS Coffee Lounge, TCPL and Reading Room) until 3 pm on Friday, although participants are still required to checkout of the guest rooms by 12 noon. (Front Desk - Professional Development Centre) |

12:00 - 13:30 | Lunch from 11:30 to 13:30 (Vistas Dining Room) |