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SEMINARS 2012​

JOURNAL CLUB

 

12/10/12

 

Speaker: Carmen Nuñez

 

Conformal chiral boson models on twisted doubled tori and non-geometric string vacua

Spyros D. Avramis, Jean-Pierre Derendinger, Nikolaos Prezas

 

We derive and analyze the conditions for quantum conformal and Lorentz invariance of the duality symmetric interacting chiral boson sigma-models, which are conjectured to describe non-geometric string theory backgrounds. The one-loop Weyl and Lorentz anomalies are computed for the general case using the background field method. Subsequently, our results are applied to a class of (on-shell) Lorentz invariant chiral boson models which are based on twisted doubled tori...

 

http://arxiv.org/abs/arXiv:0910.0431

JOURNAL CLUB

 

24/10/12

 

Speaker: Diego Marqués

 

Non-Geometric Fluxes in Supergravity and Double Field Theory

David Andriot, Olaf Hohm, Magdalena Larfors, Dieter Lust, Peter Patalong

 

http://arxiv.org/abs/arXiv:1204.1979

 

&

 

A bi-invariant Einstein-Hilbert action for the non-geometric string

Ralph Blumenhagen, Andreas Deser, Erik Plauschinn, Felix Rennecke

 

http://arxiv.org/abs/arXiv:1210.1591

SEMINAR

 

31/10/12

 

Speaker: Alejandro Rosabal

 

U-duality invariant geometry

 

JOURNAL CLUB

 

08/11/12

 

Speaker: Victor Penas

 

Large Gauge Transformations in Double Field Theory

Olaf Hohm, Barton Zwiebach

 

Finite gauge transformations in double field theory can be defined by the exponential of generalized Lie derivatives. We interpret these transformations as `generalized coordinate transformations' in the doubled space by proposing and testing a formula that writes large transformations in terms of derivatives of the coordinate maps. Successive generalized coordinate transformations give a generalized coordinate transformation that differs from the direct composition of the original two. Instead, it is constructed using the Courant bracket. These transformations form a group when acting on fields but, intriguingly, do not associate when acting on coordinates.

 

http://arxiv.org/abs/arXiv:1207.4198

JOURNAL CLUB

 

22/11/12

 

Speaker: Diego Marqués

 

Double Field Theory and Gauged Supergravities: closure versus stWrong constraints

 

JOURNAL CLUB

 

11/12/12

 

Speaker: Carmen Nuñez

 

(Non-)commutative closed string on T-dual toroidal backgrounds

David Andriot, Magdalena Larfors, Dieter Lust, Peter Patalong

 

In this paper we investigate the connection between (non-)geometry and (non-)commutativity of the closed string. To this end, we solve the classical string on three T-dual toroidal backgrounds: a torus with H-flux, a twisted torus and a non-geometric background with Q-flux. In all three situations we work under the assumption of a dilute flux and consider quantities to linear order in the flux density. Furthermore, we perform the first steps of a canonical quantization for the twisted torus, to derive commutators of the string expansion modes...

 

http://arxiv.org/abs/arXiv:1211.6437

JOURNAL CLUB

 

20/12/12

 

Speaker: Victor Penas

 

On the Riemann Tensor in Double Field Theory

Olaf Hohm, Barton Zwiebach

 

&

 

Towards an invariant geometry of double field theory

Olaf Hohm, Barton Zwiebach

 

 

http://arxiv.org/abs/arXiv:1112.5296

 

http://arxiv.org/abs/arXiv:1212.1736

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