Accueil >
Production scientifique
Théorie des Champs & Physique Mathématique
(10) Production(s) de l'année 2021
|
|
Comment on the paper “Improving Poor Man’s Kramers-Kronig analysis and Kramers-Kronig constrained variational analysis” 
Auteur(s): Rousseau E., Izard N., Bantignies J.-L., Felbacq D.
(Article) Publié:
-Spectrochimica Acta Part A Molecular And Biomolecular Spectroscopy [1994-...], vol. 259 p.119849 (2021)
Texte intégral en Openaccess : 
Ref HAL: hal-03228703_v1
DOI: 10.1016/j.saa.2021.119849
Exporter : BibTex | endNote
Résumé: We clarify some analytical expressions existing in the literature, • Within the correct formulae we conclude that there is no need for an ad hoc improvement on the opposite to the title paper, • We highlight the symmetry properties of the function to be integrated in order to agree with the usual assumptions made to derive the Kramers-Kronig relations, • The analytical formula we provide may be used to increase the accuracy of the "Poor Man's Kramers-Kronig analysis" method and the "Kramers-Kronig constrained variational analysis" method.
|
|
|
|
Negative cosmological constant in the dark sector?
Auteur(s): Calderon R., Gannouji Radouane, L'Huillier Benjamin, Polarski D.
(Article) Publié:
Physical Review D, vol. 103 p.023526 (2021)
Texte intégral en Openaccess : 
Ref HAL: hal-03184607_v1
DOI: 10.1103/PhysRevD.103.023526
WoS: WOS:000609014700004
Exporter : BibTex | endNote
Résumé: We consider the possibility that the dark sector of our Universe contains a negative cosmological constant dubbed λ. For such models to be viable, the dark sector should contain an additional component responsible for the late-time accelerated expansion rate (X). We explore the departure of the expansion history of these models from the concordanceΛ cold dark matter (ΛCDM) model. For a large class of our models, the accelerated expansion is transient with a nontrivial dependence on the model parameters. All models with wX>−1 will eventually contract and we derive an analytical expression for the scale factor a(t) in the neighborhood of its maximal value. We find also the scale factor for models ending in a Big Rip in the regime where dustlike matter density is negligible compared to λ. We address further the viability of such models, in particular when a high H0 is taken into account. While we find no decisive evidence for a nonzero λ, the best models are obtained with a phantom behavior on redshifts z≳1 with a higher evidence for nonzero λ. An observed value for h substantially higher than 0.70 would be a decisive test of their viability.
|
|
|
|
Vafa-Witten invariants from modular anomaly
Auteur(s): Alexandrov S.
(Article) Publié:
Communications In Number Theory And Physics, vol. 15 p.149-219 (2021)
Texte intégral en Openaccess :
Ref HAL: hal-02571374_v1
Ref Arxiv: 2005.03680
DOI: 10.4310/CNTP.2021.v15.n1.a4
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: Recently, a universal formula for a non-holomorphic modular completion of the generating functions of refined BPS indices in various theories with $N=2$ supersymmetry has been suggested. It expresses the completion through the holomorphic generating functions of lower ranks. Here we show that for $U(N)$ Vafa-Witten theory on Hirzebruch and del Pezzo surfaces this formula can be used to extract the holomorphic functions themselves, thereby providing the Betti numbers of instanton moduli spaces on such surfaces. As a result, we derive a closed formula for the generating functions and their completions for all $N$. Besides, our construction reveals in a simple way instances of fiber-base duality, which can be used to derive new non-trivial identities for generalized Appell functions. It also suggests the existence of new invariants, whose meaning however remains obscure.
|
1 2
