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Physique Théorique
(51) Production(s) de l'année 2020
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S-duality and refined BPS indices 
Auteur(s): Alexandrov S., Manschot Jan, Pioline Boris
(Article) Publié:
Communications In Mathematical Physics, vol. 380 p.755–810 (2020)
Texte intégral en Openaccess : 
Ref HAL: hal-02313772_v1
Ref Arxiv: 1910.03098
DOI: 10.1007/s00220-020-03854-6
WoS: 000574083100002
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: Whenever available, refined BPS indices provide considerably more information on the spectrum of BPS states than their unrefined version. Extending earlier work on the modularity of generalized Donaldson-Thomas invariants counting D4-D2-D0 brane bound states in type IIA strings on a Calabi-Yau threefold $\mathfrak{Y}$, we construct the modular completion of generating functions of refined BPS indices supported on a divisor class. Although for compact $\mathfrak{Y}$ the refined indices are not protected, switching on the refinement considerably simplifies the construction of the modular completion. Furthermore, it leads to a non-commutative analogue of the TBA equations, which suggests a quantization of the moduli space consistent with S-duality. In contrast, for a local CY threefold given by the canonical bundle over a complex surface $S$, refined DT invariants are well-defined, and equal to Vafa-Witten invariants of $S$. Our construction provides a modular completion of the generating function of these refined invariants for arbitrary rank. In cases where all reducible components of the divisor class are collinear (which occurs e.g. when $b_2(\mathfrak{Y})=1$, or in the local case), we show that the holomorphic anomaly equation satisfied by the completed generating function truncates at quadratic order. In the local case, it agrees with an earlier proposal by Minahan et al for unrefined invariants, and extends it to the refined level using the afore-mentioned non-commutative structure. Finally, we show that these general predictions reproduce known results for $U(2)$ and $U(3)$ Vafa-Witten theory on $\mathrm{P}^2$, and make them explicit for $U(4)$.
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Defying the laws of Gravity I: Model-independent reconstruction of the Universe expansion from growth data
Auteur(s): L'Huillier Benjamin, Shafieloo Arman, Polarski D., Starobinsky Alexei A.
(Article) Publié:
Monthly Notices Of The Royal Astronomical Society, vol. 494 p.819-826 (2020)
Texte intégral en Openaccess :
Ref HAL: hal-02178711_v1
Ref Arxiv: 1906.05991
Ref INSPIRE: 1739993
DOI: 10.1093/mnras/staa633
WoS: 000535885900062
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
10 Citations
Résumé: Using redshift space distortion data, we perform model-independent reconstructions of the growth history of matter inhomogeneity in the expanding Universe using two methods: crossing statistics and Gaussian processes. We then reconstruct the corresponding history of the Universe background expansion and fit it to Type Ia supernovae data, putting constraints on (Ω_m, 0, σ_8, 0). The results obtained are consistent with the concordance flat-ΛCDM model and General Relativity as the gravity theory given the current quality of the inhomogeneity growth data.
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