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Fivebrane instantons in Calabi-Yau compactifications
Auteur(s): Alexandrov S., Banerjee S.
(Article) Publié:
Physical Review D, vol. 90 p.041902(R) (2014)
Texte intégral en Openaccess :
Ref HAL: hal-00958486_v1
Ref Arxiv: 1403.1265
DOI: 10.1103/PhysRevD.90.041902
WoS: 000341287800002
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
11 Citations
Résumé: We provide the last missing piece of the complete non-perturbative description of the low energy effective action emerging from Calabi-Yau compactifications of type II string theory --- NS5-brane instanton corrections to the hypermultiplet moduli space $M_H$. We find them using S-duality symmetry of the type IIB formulation. The result is encoded in a set of holomorphic functions on the twistor space of $M_H$ and includes all orders of the instanton expansion.
Commentaires: 5 pages
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Canonical structure of tetrad bigravity
Auteur(s): Alexandrov S.
(Séminaires)
School of Mathematical Sciences (Nottingham, GB), 2013-11-28
Résumé: 'll discuss a recently proposed tetrad formulation of bimetric
gravity. Like generic massive gravity theories, bigravity models
suffer from the presence of a certain ghost scalar field.
Recently, it was argued however that there are 3 potentials which
are free from this pathology. Although the original formulation of
these potentials is quite nasty, they take a beautiful form in
terms of the tetrads. I'll present the canonical analysis of this
tetrad reformulation and confirm that it is ghost-free describing
the seven degrees of freedom of a massless and a massive
gravitons.
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Twistor approach to string compactifications, NS5-branes and integrability
Auteur(s): Alexandrov S.
(Séminaires)
Institut Henri-Poincaré (Paris, FR), 2013-06-26
Résumé: I'll review the progress achieved in constructing the non-perturbative
hypermultiplet moduli space using twistorial methods.
The metric on this space determines the low-energy effective action
of Type II string theory compactified on a Calabi-Yau threefold.
It receives instanton corrections due to D-branes and NS5-branes
and I'll show how all of them can be nicely incorporated at the level
of the twistor space. However, so far this construction has provided
NS5-instantons only in the one-instanton approximation, so that they
represent the last missing piece of the full non-perturbative picture.
I'll argue that the inclusion of these corrections may be closely related
to quantization of a certain integrable structure.
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Quantum Hypermultiplet Moduli Spaces in N=2 String Vacua: A Review
Auteur(s): Alexandrov S., Manschot Jan, Persson Daniel, Pioline Boris
Conference: STRING-MATH 2012 (Bonn, DE, 2015)
Actes de conférence: Proceedings of Symposia in Pure Mathematics, vol. 90 p.181-211 (2015)
Texte intégral en Openaccess :
Ref HAL: hal-00808906_v1
Ref Arxiv: 1304.0766
DOI: 10.1090/pspum/090/01523
WoS: WOS:000376419100009
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
15 Citations
Résumé: The hypermultiplet moduli space M_H in type II string theories compactified on a Calabi-Yau threefold X is largely constrained by supersymmetry (which demands quaternion-Kählerity), S-duality (which requires an isometric action of SL(2, Z)) and regularity. Mathematically, M_H ought to encode all generalized Donaldson-Thomas invariants on X consistently with wall-crossing, modularity and homological mirror symmetry. We review recent progress towards computing the exact metric on M_H, or rather the exact complex contact structure on its twistor space.
Commentaires: 31 pages; Contribution to the Proceedings of String Math 2012
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Canonical structure of Tetrad Bimetric Gravity
Auteur(s): Alexandrov S.
(Article) Publié:
General Relativity And Gravitation, vol. 46 p.1639 (2014)
Texte intégral en Openaccess :
Ref HAL: hal-00862720_v1
Ref Arxiv: 1308.6586
DOI: 10.1007/s10714-013-1639-1
WoS: 000333634900026
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
23 Citations
Résumé: We perform the complete canonical analysis of the tetrad formulation of bimetric gravity and confirm that it is ghost-free describing the seven degrees of freedom of a massless and a massive gravitons. In particular, we find explicit expressions for secondary constraints, one of which is responsible for removing the ghost, whereas the other ensures the equivalence with the metric formulation. Both of them have a remarkably simple form and, being combined with conditions on Lagrange multipliers, can be written in a covariant way.
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Modularity, Quaternion-Kahler spaces and Mirror Symmetry
Auteur(s): Alexandrov S., Banerjee S.
(Article) Publié:
Journal Of Mathematical Physics, vol. 54 p.102301 (2013)
Texte intégral en Openaccess :
Ref HAL: hal-00834815_v1
Ref Arxiv: 1306.1837
DOI: 10.1063/1.4826603
WoS: 000326638100015
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
7 Citations
Résumé: We provide an explicit twistorial construction of quaternion-Kahler manifolds obtained by deformation of c-map spaces and carrying an isometric action of the modular group SL(2,Z). The deformation is not assumed to preserve any continuous isometry and therefore this construction presents a general framework for describing NS5-brane instanton effects in string compactifications with N=2 supersymmetry. In this context the modular invariant parametrization of twistor lines found in this work yields the complete non-perturbative mirror map between type IIA and type IIB physical fields.
Commentaires: 28 pages. We are grateful to Carlos Contou-Carrere, Daniel Persson, and Boris Pioline for useful discussions.
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Chiral description of massive gravity
Auteur(s): Alexandrov S., Krasnov Kirill, Speziale Simone
(Article) Publié:
Journal Of High Energy Physics, vol. 2013 p.068 (2013)
Texte intégral en Openaccess :
Ref HAL: hal-00766632_v1
Ref Arxiv: 1212.3614
DOI: 10.1007/JHEP06(2013)068
WoS: WOS:000321381800014
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
22 Citations
Résumé: We propose and study a new first order version of the ghost-free massive gravity. Instead of metrics or tetrads, it uses a connection together with Plebanski's chiral 2-forms as fundamental variables, rendering the phase space structure similar to that of SU(2) gauge theories. The chiral description simplifies computations of the constraint algebra, and allows us to perform the complete canonical analysis of the system. In particular, we explicitly compute the secondary constraint and carry out the stabilization procedure, thus proving that in general the theory propagates 7 degrees of freedom, consistently with previous claims. Finally, we point out that the description in terms of 2-forms opens the door to an infinite class of ghost-free massive bi-gravity actions.
Commentaires: 25 pages
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