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Théorie des Champs & Physique Mathématique
(9) Production(s) de l'année 2022
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Black holes and modularity
Auteur(s): Alexandrov S.
Conférence invité: 2nd Marseille-Lyon LQG meeting (Marseille, FR, 2022-11-24)
Résumé: I'll explain the role of modular symmetry in the counting of black hole microstates.
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Supersymmetric black holes and modularity 
Auteur(s): Alexandrov S.
Conférence invité: Théorie, Univers et Gravitation (Montpellier, FR, 2022-10-04)
Ref HAL: hal-03811118_v1
Exporter : BibTex | endNote
Résumé: I'll give a review of the role that modular symmetry plays in description of BPS black holes and counting of their microstates.
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Topological aspects of periodic and aperiodic photonic crystals
Auteur(s): Rousseau E., Kling Emmanuel, Felbacq D.
Conference: SPIE Nanoscience + Engineering (San Diego, FR, 2022-08-21)
Texte intégral en Openaccess : 
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D-instantons in Calabi-Yau compactifications
Auteur(s): Alexandrov S.
Conférence invité: String Field Theory 2022 (Prague, CZ, 2023-09-12)
Ref HAL: hal-03811120_v1
Exporter : BibTex | endNote
Résumé: Euclidean D-branes wrapped on non-trivial cycles of a Calabi-Yau threefold are known to affect the metric on the hypermultiplet moduli space determining the effective action of type II strings on such manifolds. After reviewing the existing results on the instanton corrected metric following from a combination of constraints imposed by supersymmetry and dualities, I'll show how the D-instanton effects can be computed by a direct worldsheet approach. This required solving several conceptual and technical problems, which also paved the way for extension of this approach to compactifications with lower supersymmetry. The talk is based on joint work with A. Sen and B. Stefanski.
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Joyce structures, twistors and topological strings
Auteur(s): Alexandrov S.
Conférence invité: BPS states, mirror symmetry, and exact WKB II (Sheffield, GB, 2022-09-05)
Ref HAL: hal-03811147_v1
Exporter : BibTex | endNote
Résumé: As shown by T. Bridgeland, a Riemann-Hilbert problem determined by Donaldson-Thomas invariants naturally gives rise to the so-called Joyce structure. It can be characterized by a function known as Plebanski potential, or its close cousin Joyce potential. I'll show that a twistorial solution to the RH problem provides a simple integral expressions for both potentials. Then I'll explain the relation of this solution to the conformal limit of the twistor spacesappearing in gauge and string theories, and physical interpretation acquired bythe two potentials in these setups. For the case of the resolved conifold, I'll present a recipe to make the twistorial solution well-defined despite an infinite BPS spectrum, and trace out the emergence of a tau-function, its relation to topological strings and its behavior under S-duality to the twistorial implementation of instantons in string theory.
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Joint reconstructions of growth and expansion histories from stage-IV surveys with minimal assumptions I: Dark Energy beyond $\Lambda$
Auteur(s): Calderon R., L'Huillier Benjamin, Polarski D., Shafieloo Arman, Starobinsky Alexei A.
(Article) Publié:
Physical Review D, vol. 106 p.083513 (2022)
Texte intégral en Openaccess : 
Ref HAL: hal-03722260_v1
Ref Arxiv: 2206.13820
Ref INSPIRE: 2102704
DOI: 10.1103/PhysRevD.106.083513
WoS: 000875169200002
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
2 Citations
Résumé: Combining Supernovae, Baryon Acoustic Oscillations and Redshift-Space Distortions data from the next generation of (Stage-IV) cosmological surveys, we aim to reconstruct the expansion history up to large redshifts using forward-modeling of $f_{\mathrm DE}(z) = \rho_\mathrm{DE}(z)/\rho_\mathrm{DE,0}$ with Gaussian processes (GP). In order to reconstruct cosmological quantities at high redshifts where few or no data are available, we adopt a new approach to GP which enforces the following minimal assumptions: a) Our cosmology corresponds to a flat Friedman-Lemaître-Robertson-Walker (FLRW) universe; b) An Einstein de Sitter (EdS) universe is obtained on large redshifts. This allows us to reconstruct the perturbations growth history from the reconstructed background expansion history. Assuming various DE models, we show the ability of our reconstruction method to differentiate them from $\Lambda$CDM at $\gtrsim2\sigma$.
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D-instantons and superpotential
Auteur(s): Alexandrov S.
Conférence invité: Strings and Geometry 2022 (Utrecht, NL, 2022-05-02)
Ref HAL: hal-03664125_v1
Exporter : BibTex | endNote
Résumé: I'll present the computation of a D-instanton induced superpotential in an orientifold Calabi-Yau compactification of type II string theory using a direct worldsheet approach.
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